NOTES ON THE LITERATURE OF EXPLOSIVES.
By Charles E. Munroe.
No. XXIII.
The Fifteenth Annual Report of H.M. Inspectors of Explosives, being for the year 1890, shows that though the rigid system of inspection and supervision of explosives factories and magazines, for which this corps is famous, has been maintained, it has not retarded the growth of this important industry, for during the past five years the number of factories in operation has increased from 108 to 123, while the number of persons employed has increased from 7484 to 9820. Notwithstanding this increase in production, the number of accidents occurring during the manufacture and use or abuse of explosives was 132, resulting in 44 killed and 85 wounded, while the average number of accidents for the past ten years was 137.8, resulting, on the average, in 41.4 killed and 102.6 wounded.
No statistics regarding production are given in these reports. This is very much to be regretted, as they would prove a most valuable criterion by which to measure the value and operation of the Explosives Act. Statistics are, however, given for importations, from which it appears that there was an extraordinary decrease in the amount of dynamite imported in 1890, it being but 371,650 pounds, as against an average yearly importation of 1,000,000 pounds for the past eight years. Part of this was accounted for by the increase in the amount of the gelatine explosives, yet the total of all nitroglycerine explosives imported was less than for 1889 by over 400,000 pounds. 38,000 pounds of bellite, 9700 pounds of fulminate, and 10,950,000 detonators were also imported.
Dr. Dupre's report shows that in 1890, for the first time, the number of samples of gelatinized preparations examined exceeded those of dynamite, and points out that this increased use is due to these bodies being practically unaffected by water, and capable of being graduated in strength with greater readiness than obtains for dynamite, while in addition their plastic nature renders them more easy of use in bore-holes. These explosives are not free, however, from dangers of their own; dangers which manufacturers have not, as yet, completely overcome. The chief of these is their liability to exude. There is also a greater difficulty in insuring absolute stability under the most trying conditions of temperature and storage. Since the establishment of the manufacture of dynamite on a large scale, no authentic case of its spontaneous ignition is on record; whereas there are several such in regard to gelatinized preparations.
The consumption of dynamite is also being affected by the introduction of ammonite, bellite, roburite, securite, etc., whose greater insensitiveness to percussion and friction gives the advantage of somewhat greater safety in manufacture and use.
The different results obtained by different analysts in applying the "heat test" to blasting gelatine and its class has led to a precise description of the French chalk to be used.
For the assistance of inventors who desire to have explosives examined, a memorandum giving the necessary steps to be taken is printed in this report.
The chapter on accidents by fire or explosion, which is a characteristic and important feature of these most valuable reports, occupies some thirty-seven pages, and as usual includes a summary review of the accidents reported from abroad, as well as those occurring at home. It is noted that in the explosion of 80 tons of gunpowder at the Dupont works, October 7, 1890, a larger quantity was involved than in any previous accidental gunpowder explosion. The accidental explosion next in magnitude was that of Erith in 1864, when 57 ½ tons of powder exploded. The Louisiana, which was intentionally blown up before Fort Fisher in 1864, contained 200 tons of gunpowder. The author, in commenting on this, is misled by our complicated geographical nomenclature.
Extracts from this record of accidents and of that of experiments will be found later on.
Lt. Willoughby Walke, Second Artillery U. S. A., gives in Jour. Am. Chem. Soc. 12, 256-274; 1890, the results of his "Determination of the Strength of Various High Explosives" by the use of the Quinan pressure gauge, in which he employed nitroglycerine made by the Naval Torpedo Station method and carefully stored until it was thoroughly "clear," as the standard. This period of rest of several months was found necessary, as the strength of the explosive varied from day to day until it had "cleared," after which it remained constant.
U.S. Letters Patent No. 455,217, June 30, 1891 have been granted Carl Lamm for an invention, the object of which is to provide an explosive less dangerous than nitroglycerine in its manufacture, transportation, and use.
He describes this explosive as being in the nature of a compound consisting of a nitrate (such as nitrate of ammonia, of potassa, of soda, or of baryta) and dinitro-benzine, or dinitro-benzol mixed in such proportions that when exploded the hydrogen of the dinitro-benzine or dinitro-benzol burns and forms water, and the carbon of the same material forms carbonic acid at the expense of the oxygen contained in the nitrate conjointly with the oxygen contained in the dinitro-benzine. He has also had in view the protection of the nitrates from the influence of moisture, and for this reason the dinitro-benzine or dinitro-benzol, which is a solid, is pulverized, as is also the solid nitrate, and both are then mixed and heated by steam in suitable molds to 212° F., which causes the dinitro-benzine or dinitro-benzol to melt between 176° and 212° F., and to completely envelope the particles of saltpeter or other nitrate used. The mass solidifies in cooling, and is molded into cartridges or bodies of any suitable shape, or it may be pulverized or granulated.
He has found the following proportions of ingredients to give the best results: dinitro-benzine, one part, and nitrate of ammonia, at least 1.9 parts; dinitro-benzine, one part, and nitrate of potassa, 0.96 part; dinitro-benzine, one part, and nitrate of baryta, 1.24 parts; dinitro-benzine, one part, and nitrate of soda, 0.81 part.
The above proportions are so selected as to yield or form carbonic oxide and water on explosion.
If the proportion of saltpeter or other nitrate be increased about three times, carbonic acid and water will be formed, which gives the best results for mining purposes.
He states the advantages of this explosive as: Impossibility of explosion from shock or blow; non-ignition by fire; possession of more power than other high explosives; non-congelation at a low temperature; pulverization without danger previous to use; safety in transportation and storage; advantageous use in coal mines in place of gunpowder, and requiring from a fourth to a fifth only of the quantity.
He claims: 1. An explosive compound composed of a nitrate salt and dinitro-benzine or dinitro-benzol substantially as and for the purpose specified; 2. an explosive compound composed of nitrate of ammonia and dinitro-benzine or dinitro-benzol, substantially as described.
In his improvements relating to the manufacture of nitrocellulose or pyroxyline, English Patent 20,978, Dec. 23, 1890, G. M. Mowbray uses, as raw material, cotton rags, cotton lint from cotton-seed hulls, and other materials, instead of fine pure unsized cotton tissue paper, and first steeps it in a bath of a salt, preferably a nitrate, and then passes it between rollers and slowly dries it. The salt crystallizes in the cells of the fiber, and this action opens up the cells so that when the material is subsequently immersed in the acid bath, nitration takes place more rapidly and is effected at less cost than by the present process. It is pointed out that, although a nitrate is preferred, "any salt crystallized, or even water crystallized by freezing, in the cells of the fibrous cellulose, facilitates nitration by rendering the inner walls of the cellular tissue more readily accessible to the acids of the immersion bath."—Jour. Soc. Chem. Ind. 10, 271; 1891.
U. S. Letters Patent No, 454,281, June 16, 1891, have been granted Hiram S. Maxim for "Method of Making Gun-Cotton." He claims to render available, by this method, all the valuable properties of the acids, and to be able to use such acids until they have become entirely spent, or until they have parted with nearly all their constituents that go to effect the nitration of the cotton. The method involves the employment of a series of six receptacles or vats filled with a mixture of the strongest acids procurable. These vats are arranged on a table or platform, mounted so as to turn about a central pivot or shaft.
In using this apparatus a given quantity of cotton is immersed, say, in vat 1. It is then removed and freed from the excess of acid by any suitable means, such as a centrifugal separator. The acid separated from the cotton is returned to the vat from which it was taken. The cotton is then immersed in vat 2, and again freed from the absorbed acids by the separator, the table, prior to such separation, being turned so that the acid from the discharge of the separator will be delivered to vat 2, from whence it came. In the same manner the cotton is dipped in succession in each vat, and the surplus acid squeezed from it back into its appropriate tank. After successive charges of cotton have thus been treated the acid becomes weakened or spent, that in the first vat of the series to the greatest degree, and in each succeeding vat to a less extent. As long, however, as the strength of acid in the last vat is sufficient to secure the desired result and there remains in the first vat sufficient strength to partially convert the cotton, no replenishing of the acid is necessary; but as soon as the acid in the first or last vat of the series falls below the required strength, the spent acid from vat 1 is replaced by fresh, strong acid; thus, in the order of the strength of acid contained in them, vat 2 now becomes the first of the series or that containing the weakest acid, and vat 1 the last of the series. The subsequent charges of cotton are then immersed in vat 2 first, and in vat 1 last, until the spent acid in vat 2 is replaced by fresh, strong acid, when in its turn vat 3 becomes the first of the series, and so on. In this way all the suitable properties of the acid are utilized, the weakest acids becoming weaker by the partial conversion of the cotton which they affect, while the last immersions of each charge of cotton are in the strongest acid.
The invention is not limited to the special apparatus described, in which a conventional form of centrifugal separator is employed; and any suitable means may be used for expressing the acid from the cotton.
He claims as his invention:
1. The method of manufacturing gun-cotton by immersing or treating charges of cotton in a given order in each of a series of receptacles or vats of acid, and as the acid in said vats becomes spent or weakened, replacing the weakest acid of the first vat of the series with fresh, strong acid, and changing the order of immersion or treatment of the succeeding charges of cotton in accordance with the relative strength of acid in the series of vats.
2. The method of manufacturing gun-cotton, which consists in immersing or treating charges of cotton in a given order in each of a series of tanks or vats of acid, and expressing from the cotton the excess of acid taken up by it and returning such excess to the vat from whence it was taken, then as the acid in said vats becomes spent or weakened, replacing the weakest acid of the first vat of the series with fresh, strong acid, and changing the order of immersion on treatment of the succeeding charges of cotton in accordance with the relative strength of the acid in the series of vats.
Hilaire De Chardounet, of France, has been granted U.S. Letters Patent No. 455,245, dated June 30, 1891. He also holds an English patent for the same invention.
The invention introduces certain improvements in the manufacture of nitrocellulose or pyroxyline, which pertain to the processes of nitration and washing, and the recovery of the acids.
It is said that the processes used permit the reduction to a minimum of the waste of acids, and the obtaining a pure pyroxyline, the nitration of whose fibers differs only in a very small percentage.
The nitration is effected by introducing cotton fiber or any other cellulose (ramie, hemp, purified wood pulp, rags, etc.), previously well dried by heat, into large pots previously filled about three-quarters full with the acid mixture, prepared in the ordinary proportions and kept at a fixed temperature by a steam-jacket. The concentration of the acids and the temperature are determined, as usual, by the degree of nitration desired; e.g. if it is desired to obtain a soluble pyroxyline, to one kilogram of dry cotton use twelve liters of nitric acid at the density of 1.34, and 18 liters of sulphuric acid at the density of 1.83. After leaving to soak for a time, which may vary from 1 to 24 hours, or even more, the pots are raised and poured into a centrifugal machine lined with lead or caoutchouc. By this machine the acid is extracted and run off into a reservoir, after which the communication with the reservoir is shut off and the material is washed.
The washing is done by the use of a large quantity of water, and either by removing the acid fiber to a separate vat or by leaving it in the centrifugal machine, in either case taking care to prevent any increase of temperature.
The recovery of the nitric acid left in the mass by the centrifugal machine may be made as follows: The first rinsing water may be neutralized either by adding each time an alkaline carbonate, or by placing at the bottom of the vat some fragments of limestone. A new quantity of pyroxyline may then be rinsed in the same water without inconvenience, and this may be repeated successively until this water is sufficiently charged with nitrate to be advantageously evaporated. The nitrate of lime, if desired, may be transformed into alkaline nitrate by sulphate of soda (always existing in abundance in the manufacture of nitric acid), and the nitrate of soda, after being revivified, may serve anew in the manufacture of nitric acid. After the first rinsing the material is deposited in a centrifugal machine so constructed that it may be filled with water. The first centrifugal may serve the purpose if thus constructed. The material is then successively dried by the centrifugal action, and washed with a large quantity of water while turning the machine slowly. This succession of drying and washing permits a perfect cleansing to be rapidly effected by twelve or fifteen alternations. All the washings should be made with pure water as cold as possible. For wetting the fiber between the centrifugal drying operations the machine may be turned slowly and the water thrown on the mass of pyroxyline; but the water must be very pure in order not to leave any deposit in the mass.
It is claimed the invention has the following defined novel features or improvements, viz. The described improvement in the manufacture of pyroxyline, consisting in the successive steps of nitration, centrifugal extraction of spent acids, washing of the pyroxyline, and neutralization of the wash water by an alkaline or basic material for the recovery of the residue of nitric acid left in the pyroxyline by the centrifugal action.
The described improvement in the manufacture of pyroxyline, consisting in the successive steps of nitration, centrifugal extraction of acids, washing with water to remove the acid left after the centrifugal extraction, neutralization of the acid in this water, and its re-use with successive quantities of pyroxyline, and successive alternations of washing with water, and centrifugal dryings of each quantity of pyroxyline.
In his description of the "Preparation of Cotton-Waste for the Manufacture of Smokeless Powder," Centrol. f. Textil. Ind. 21, 975; 1890, A. Hertzog states that the military authorities require a cotton which, when thrown into water, sinks in two minutes; when nitrated, does not disintegrate; when treated with ether, yields only 0.9 per cent of fat; and containing only small traces of chlorine, lime, magnesia, iron, sulphuric acid, and phosphoric acid. The waste from the spinning machines and the looms is boiled with soda-lye under pressure, washed, bleached with chlorine, washed, treated with sulphuric or hydrochloric acid, washed, centrifugaled, and then dried. When the cotton is very greasy it is first boiled with lime water. The loss in these treatments varies largely; for example: Moisture, 3-15 per cent; packing, and in transit, 2-5 per cent; boiling and washing, 5-40 per cent; bleaching, 1.5-20 per cent.—J. Soc. Chem. Ind. 10, 161; 1891.
U. S. Letters Patent No. 420,445, of February 4, 1890, have been granted Joseph R. France, who claims to have invented certain new and useful Improvements in Soluble Nitrocellulose and its Process of Manufacture.
According to his statement, soluble nitrocellulose as hitherto made is not uniform in its character and qualities. His object is to secure an article that is uniform in these respects, and therefore reliable for the purposes to which it is adapted, and this by an easier and more certain process than that hitherto employed.
Heretofore it has been customary, according to one method, to first free the cotton from impurities by washing it in an alkaline solution; second, wash it in pure water; and third, dry it. It is then passed into a bath containing the mixed acids, which are kept at an even temperature of about 60°, by means of ice in hot weather and warm water in cold weather, and there allowed to remain for a length of time, according to the condition and nature of the fiber, the strength of the acids, etc., until the desired chemical changes are supposed to have taken place. When it is removed, the acid is first pressed out by repeated plunging into clear water. Some objections to this method of treatment are, that the action of the mixed acids upon the cotton fiber is slow, irregular and imperfect, and cannot be subjected to any uniform rule. Both expense and care are required to maintain the even temperature, notwithstanding which, some lots will reach the point of "nitration" much sooner than others, necessitating constant watchfulness.
His explanation of the slow, irregular and imperfect action of the acids in the above-mentioned process is, that however uniform the mixed acids may be in strength and proportions, and however carefully the manipulations may be conducted, there are variable elements found in different samples of cotton which defy prognosis and defeat any regular system of rules. The cotton fiber has for its protection a glazed surface, as it were, enameled by nature. It is tubular and cellular in structure, and contains a natural lubricating semi-fluid substance, composed of characteristic oil, or gum, or water, or other material, or a combination thereof. Both the glaze and the lubricating substance vary with the soil, the climate and other accidents of growth, as do other characteristics of the fiber. The tubes of the fiber seem to be open at one end only, when the fiber is of normal length.
Some or all of these elements play their parts in resisting or otherwise modifying the action of the acids upon the fiber. When the cotton is subjected to the action of the acids in its natural state and length of fiber, the line of least resistance seems to be by way of the inside of the tubes constituting the fiber of the cotton, into which they are taken in part by capillary attraction, subject to change themselves as they progress, and to the increased resistance from the oil or the gum, etc., in their progress, and therefore to modified action, the result of which is slower and slower and otherwise more and more imperfect chemical change. It may also be that the power of capillary attraction is balanced in the tubes by air contained therein, after a little, sufficiently to prevent the acids from taking full effect. These objections he overcomes in the manner to be shown hereinafter.
Another method consists in making the cotton up into yarn and hanks, and treating it in that form with acids in the usual manner. It is found that the twisting of the fibers and the disposition in the yarn form, and the forming of hanks there from, causes a certain resistance to the penetration and to the action of the acids, with the result that parts of the fibers are not acted upon or acted upon imperfectly.
Still another method consists in taking paper expressly prepared from cotton fiber for the purpose, passing it through the acids, washing, drying, grinding, etc., as before described. In this last case the fibers are of course modified both by the chemical and also by the mechanical treatment to which they have been subjected in the preliminary preparation of the paper; but if the oil or gum or the glaze has been attacked by them, and if they, all of them, have been removed by subsequent washing, etc. (which is very difficult, if not impossible to do), the character of the cotton fiber itself seems to have been changed chemically, mechanically, and by felting, so that the cellulose product of the paper process is not uniform or otherwise always satisfactory. In all these methods temperature is found to be an important condition.
He uses the cotton fiber in its natural state, made pure and free from extraneous substances as possible, but cut, pulverized or ground in advance as fine as possible, even to a dust, by the mechanical means and to the extent set forth in an application filed by him February 5, 1884, Serial No. 119,845, and in that condition subjects it to the acids and to all the subsequent manipulations required to produce soluble nitrocellulose, to be described hereinafter. The principle of his method is that, whereas in the first-named old process the acids attack the fiber, say of half an inch or an inch in length, from one end and the outside, in his process, when any natural cotton dust is used, each particle will have two more mouths or openings by which the acids can enter for every additional piece into which the fiber is cut, and in addition the glaze of the fiber may be broken up by the cutting, rubbing and grinding operations to which it is subjected in advance, thereby giving the acid a better opportunity for external attack as well. In his method the cotton fiber becomes a homogeneous mass of particles or dust, consisting of very small bits of the material, each one of which is attacked by the acids and by coming in contact with the same, the result being uniform in character in the time required for nitration, and also in the uniform equivalents of nitrogen taken up in producing the desired product.
The cotton dust is placed in a bath containing the mixed acids in the usual well-known proportions required to produce the article at any ordinary temperature—between 40° and 90° F.—and allowed to remain for a uniform length of time, in proportion to the strength of the acids, until the point of nitration is reached. The surplus acids may be removed by pressure or extraction, or the nitrocellulose may be left in the acids for an indefinite length of time, according to convenience, without change, or injury, as in the process now in use.
He states that: "In my process I avoid several of the operations employed in the methods previously described, and I substitute an improved base or material to be treated, having superior qualities for the purpose, which enable me to omit some of the steps required where other base material is used, as follows:
"1. I do not find that it is necessary to wash either the cotton fiber or the cotton dust in any alkaline solution. Consequently, I omit that operation entirely, and find that I produce a superior article of nitrocellulose when it is omitted, and this with certainty in each and every instance.
"2. The washing in pure water and the drying are therefore omitted also.
"3. The watching and constant attention to the temperature I also avoid.
"4. I avoid the loss of material which occurs from premature or imperfect nitrations, and the danger of spontaneous combustion.
"5, I avoid the want of uniformity in the resulting product.
"6. I avoid both capillary obstruction and much of that arising from the enamel or glaze of the fiber.
"Among the advantages resulting from the use of my cotton dust are the following:
"1. The product is always uniform both in appearance and chemically, and will remain stable for a long period.
"2. It is always evenly soluble.
"3. It is not liable to spontaneous combustion.
"4. The remaining acids are more easily and more thoroughly washed out after the point of nitration has been reached.
"5. My soluble nitrocellulose can be more cheaply produced, since waste is avoided and time is saved in washing.
"6. Less watching of the process of nitrogenizing is required.
"The fact that the cotton is in the form of dust, and in that finely comminuted form is acted on more quickly and perfectly by the acids, is important also, and has its proper effect in the washing stage above mentioned, giving more prompt and complete access to the water and egress to the acids.
"The soluble nitrocellulose made from my cotton dust is distinguishable from its cotton dust base by its explosive quality, and by a certain dull uniform massed and slightly felted appearance, showing that it has not been subjected to mechanical disturbance subsequent to its subjection to the action of the acids. In other respects it corresponds in appearance to the cotton dust from which it is made. It is distinguishable from the highly explosive or insoluble nitrocellulose by the fact that it can be dissolved in the usual preparation of ethyl, or grain alcohol and ether, as used in making collodion, or in methyl or wood alcohol of 95 per cent to 100 per cent. It is distinguishable from soluble nitrocellulose made by the old process, which has been reduced to dust subsequent to subjection to the acids, by its appearance, as above stated, showing that it has not been subjected to mechanical disturbance subsequent to its subjection by the action of the acids.
"In practicing this invention I find that taking one-pound batches of finely ground cotton, which is immersed in the mixed acids of varied proportions according to solubility required for a good soluble nitrocellulose, a proportion of eight (8) parts nitric acid 42° Beaumé and of sulphuric acid twelve (12) parts 66° Beaum6, is suitable. The cotton is stirred into the bath of mixed acids for fifteen (15) minutes, the superabundant acids are pressed out, and the cotton then washed in successive waters until entirely free from acids. Using cotton dust, I can thus nitrate effectively at an ordinary temperature—say from 50° to 100° F. I usually prefer to keep the room in which the nitration is carried on at a temperature of about 75° F., but I find no perceptible difference in the nitrations at ordinary temperatures, as before stated, and I attribute the advantages over the old methods here indicated to the use of the cotton dust, as stated herein; but I do not desire to limit my invention either to the exact proportions of the acids or to the exact temperature above set forth, as by the use of my cotton dust I am able to vary the range both of proportions and of temperature greatly and yet accomplish the purpose of my invention in a superior manner.
"I am aware that it is not new to produce an impalpable powder from cellulose by the use of chemicals and afterwards treat the same for the production of pyroxyline or nitrocellulose, and this I do not claim."
What he does claim, as his invention, is as follows:
1. The process of making nitrocellulose, which consists in mechanically reducing cotton to a uniform and homogeneous dust-like condition, and then subjecting it to the action of a bath of nitric and sulphuric acids in about the proportions and at the temperature stated.
2. The process of making nitrocellulose, which consists of subjecting mechanically comminuted cotton in a homogeneous dust-like condition to the action of a bath of nitric and sulphuric acids in about the proportions and the temperature stated.
3. As an improved article of manufacture, soluble nitrocellulose composed of pure mechanically comminuted cotton fiber nitrated, substantially as described.
U.S. Letters Patent No. 457,002, August 4, 1891, have been granted Ebenezer Kennard Mitting, for a "Process of Making Nitro-Glycerine." In his specification, after referring to the usual manner of making nitroglycerine in the three varieties known to chemists as mononitro, dinitro, and trinitro-glycerine, and of which the trinitro is the only variety which is of practical utility as an explosive, he states that the operation is defective, owing to the fact that the last portions of the glycerine added to the acid are not converted into trinitro-glycerine, by reason of the weakening of the acid mixture by the water formed in the reaction earlier in the operation, the presence of a comparatively large excess of anhydrous or nearly anhydrous nitric acid being essential to thoroughly convert the glycerine into trinitro-glycerine. Consequently the full theoretical yield of nitroglycerine (or a close approach thereto) is never obtained in practice, a certain loss always resulting from such portion of the glycerine which has not been converted at all, or only converted into the mononitro variety, being dissolved in and carried away by the wash water, while another and variable proportion may have been converted into the dinitro variety, and a portion of this may remain after washing together with the bulk of the trinitro, reducing its specific gravity and explosive force. Various means have been proposed to overcome this defect and improve the yield of trinitro-glycerine. It was thought that the admixture of the acid with the glycerine in thin streams, allowing the whole to presently run into a collecting tank, would overcome the difficulty; but this device did not succeed, owing to the fact that the reaction is not completed, except (as stated above) in the presence of a large excess of anhydrous nitric acid. Consequently the same conditions were brought about in the collecting tank as obtained in the case of running the whole of the acid first into the tank and then adding the glycerine slowly, viz. that the last portions of the glycerine were not fully converted. Again, it was proposed to first treat the glycerine with only a portion of the usual amount of acid to remove the spent acid and then treat with the remainder, and for the better prosecution of this process to vary the quality of the acids used for the first and last treatment, and even to make the process a continuous one. So far as he was aware, this mode has not proved successful in practice, because it fell short of providing the necessary excess of nitric acid at the close of the operation. It has also been proposed to use double and treble the usual quantity of acid; but this device has not been successful, and on the other hand the cost has been so largely increased as to be almost prohibitive.
The object of his invention is to overcome the difficulty above set forth and to convert the whole or practically the whole of the glycerine into trinitro-glycerine, and thus produce a yield more nearly approaching the theoretical quantity, and to effect this improvement without the use of additional acid beyond the usual quantity now employed.
In carrying his invention into effect, he first proceeds with the nitration of the glycerine in the usual manner, viz. by charging the nitrating vessel with the mixed acid, say about 8 parts, by weight, for every 1 part of glycerine to be nitrated, and at the close of the operation and after separation has taken place he draws off the spent acid in the usual manner. In the meantime he prepares another lot of mixed acid for the next succeeding lot of glycerine; but before using it for such next lot he runs into and mixes with it the nitroglycerine produced from the first operation. The effect of this is to expose the nitroglycerine produced in the first operation to the full effect of the large charge of anhydrous nitric acid intended for the second operation, and thus convert any of the lower nitroglycerine into the trinitro variety. After allowing the mixture to settle he draws off the supernatant trinitro-glycerine to the washing tanks and proceeds with the nitration of the second lot of glycerine with the acid (originally intended for it) in the usual way, and the nitroglycerine thus produced is in its turn fed into and mixed with the lot of acid for the next succeeding nitration, and so on continuously, using always the fresh acid first upon the last preceding lot of glycerine which has been nitrated, and then to nitrate a fresh lot of glycerine, as described. The fresh acid after acting upon the product of a previous nitration contains a little water, such water being that produced in the reaction, as will be readily understood. This, however, is of comparatively small amount and does not seriously affect the succeeding nitration, especially as same is in reality completed by exposure to the next lot of fresh acid.
The foregoing operations he performs in one nitrating vessel by proceeding as follows: he first nitrates a charge of glycerine in said nitrating vessel and allows the mixture of nitroglycerine and spent acid to settle and separate, and then draws off the spent acid only, leaving the nitroglycerine in the nitrating vessel. He next runs into that nitroglycerine the charge of mixed acid intended for the next nitration (this operation is performed quickly and with perfect safety under the usual precautions), and having mixed the liquids he allows them to settle and separate, and next draws off the supernatant nitroglycerine (to be washed and otherwise dealt with) by a faucet fixed at a proper level, or equivalent means, leaving the acid in the nitrating vessel ready to receive a charge of glycerine, which he now runs into it. He next allows the mixture to settle and separate, draws off the spent acid, and proceeds to run into the nitroglycerine the charge of fresh acid, as before, and so on in regular order, as described; or two or more nitrating vessels may be employed and preferably fixed at different levels, as will be readily understood by those versed in the art. By working in this manner an increased yield of nitroglycerine is obtained, of full specific gravity and explosive power, without increased quantity of acid beyond that usually employed, and at only a slightly increased cost for manipulation, which is more than repaid by the increased yield, quality, and safety, as the fully converted trinitro-glycerine is far less liable to spontaneous decomposition than a mixture of such nitroglycerine with lower nitro compounds.
He claims:
1. The improvement in the method of manufacturing nitroglycerine, which consists in first nitrating a charge of glycerine and separating the product from the spent acid, then treating said product anew with a fresh charge of nitrating acid in excess, and finally separating the nitrated glycerine from the fresh excess charge of acid, substantially as described.
2. The improvement in the method of manufacturing nitroglycerine, which consists in first nitrating a charge of glycerine and separating the product from the spent acid, then treating said product anew with a fresh charge of nitrating acid, separating the nitrated glycerine from the acid, and employing the acid to nitrate a second charge of glycerine, substantially as described.
3. The improvement in the method of manufacturing nitroglycerine, which consists in first nitrating a charge of glycerine and drawing off the spent acid, next treating the product with a fresh charge of nitrating acid, then drawing off the nitroglycerine and nitrating a fresh charge of glycerine with the same acid, and repeating the operation in the same nitrating vessel, substantially as described.
The Scientific American Supplement 27 , 11070-11071; April 13, 1889, copies from La Nature an article by M. Vuillaume, late director of the dynamite factory at Cengio, Italy, on the "Manufactures of Nitroglycerine," which is illustrated by a number of drawings showing the apparatus used and the method of working it.
Eduard Liebert, of Berlin, has been granted two patents for methods of treating nitroglycerine. In the first he seeks to render nitroglycerine uncongealable by adding to it isoamyl nitrate. This addition, while it may not prevent freezing in all cases, is likely to weaken the effect considerably. In the second, he adds ammonium sulphate or nitrate to the acid mixture during nitration, to destroy the nitrous acid formed according to the following equation:
(NH4)2SO4 + 2HNO2 = H2SO4 + 2N2 + 4H2O.
—Ding. Poly. Journ. 278, 19; 1890.
U.S. Letters Pat. No. 449,687, April 7, 1891, have been granted Hiram S. Maxim for "Process of and Apparatus for Making Explosives."—111.
His invention relates to the manufacture of explosives of the kind or class known as "nitro compounds" or "nitrated explosives," such as nitroglycerine, gun-cotton, and the like, which result from the combination or composition with glycerine, cellulose, or the like, of nitric acid or other suitable nitrating compounds.
In his specification he describes the invention as applied to the manufacture of nitroglycerine only; but its applicability to the treatment or manufacture of other explosive compounds of a similar nature is to be understood.
The main objects of the invention are, first, to produce any desired quantity of an explosive by a continuous process or operation, and, second, to bring the acid or nitrating agent and the glycerine, or other material to be acted upon thereby, into intimate contact with each other while both are in a very finely divided condition. These objects he accomplishes by bringing the glycerine or other material in the condition of spray into a stream or current of acid spray.
In carrying out the invention practically, the mixing of the nitric acid or nitrating agent and the glycerine is effected by means of an injector operated by cold compressed air or by a cold air blast. The suction produced by the current of air flowing through a nozzle forming a part of the injector, draws the glycerine from a tank in which it is contained, and the current of air impinges upon and atomizes the glycerine, or scatters it in a fine spray. The acid is similarly drawn from another tank and blown into a fine spray, and the two substances while in this finely divided condition are caused to intermingle in the presence of air which is rapidly expanding and of which the temperature is rapidly falling. The atomized acid and glycerine are together blown into, and conveyed through, a mixing pipe or tube, and after issuing there from they are washed or quenched by a copious spray or jet of water, and collected in a suitable receiver.
The apparatus, as described, consists of a nozzle entering a "chamber" provided with a nozzle, entering the enlarged end of a "tube," the three concentric parts forming a double injector, of which the inner or first nozzle is connected with a receiver of air compressed by a suitable pump to a pressure of about 100 pounds to the square inch. Which pipe enters the "chamber" back of the orifice of the inner or first nozzle, contains a suitable cock, and leads from a tank or receiver. A second pipe, provided with a cock, leads from a second tank or receiver and enters the "tube" back of the orifice of the nozzle of the "chamber." One of the tanks is to contain the acid or nitrating agent and the other the material to be combined therewith, and both are provided with glass gauge tubes to indicate the levels of the liquids therein.
The first mentioned "tank" is filled with glycerine, and the other, to the same level, with acid. The air is then allowed to flow through the first or inner nozzle. The current of air issuing from this nozzle produces a partial vacuum in the "chamber," which, upon opening the cock of the pipe connecting with the tank of glycerine, draws the glycerine in. The air impinging upon the glycerine atomizes it and forces it in a spray through the nozzle of the "chamber." The air-jet and spray issuing from this nozzle produce in like manner a partial vacuum in the "tube" back of the orifice of said nozzle, and this draws in the acid, which, meeting the jet, is blown into spray and mixed with the atomized glycerine. The air being kept under a high pressure in the reservoir, a considerable amount of refrigeration will take place in the nozzle of the "chamber" and in the "tube" by reason of its expansion in these places, and the temperature of the acid and the glycerine will thus be prevented from rising too high.
The "tube," into which the atomized mixture of acid and glycerine is blown, serves as a mixing chamber, and should be of considerable length, so that the materials may have ample time while in the same to complete their reactions on one another in the manner required. It may be from 1 ¼ to 1 ½ inches in diameter at the part which surrounds the injector nozzle, and for a distance of, say, 16 inches, or thereabout, from the said injector, and may gradually increase in diameter beyond this point until it reaches a collecting tank. It is, moreover, advantageous to arrange said "tube" with a fall toward the collecting tank of about 1 in 15.
The length of the "tube" or mixing pipe may be from 100 to 200 feet, more or less, and a wall or mound of earth may be built between the injector and the collecting tank to serve as a protection to the operator. The "tube," as well as other parts of the apparatus, may be surrounded by a water-jacket, through which a circulation of cool water is maintained for keeping down the temperature of the explosive compound.
Prior to entering the collecting tank the current of spray is met by a stream or a number of jets of cold water from a nozzle inserted in the top of the collecting tank above the "tube" or mixing pipe, which serves to cool or quench it as it enters the collecting tank.
The tanks for containing the acid and the glycerine are preferably arranged side by side above the injector and mixing pipe or "tube," and should be made of such relative capacities or dimensions that they will contain the required proportions of acid and glycerine, and will therefore both be emptied at the same time.
The quantity of explosive material operated upon at any time is very small. The collecting tank should, however, be of large dimensions, so that it will contain a great quantity of water.
The acids and glycerine being blown into a fine spray, as above described, an instantaneous nitration will be effected, while the expansion of the air, as it issues from the injector, serves to lower the temperature. Moreover, it is claimed for this apparatus that the chemical reaction may be readily controlled, and that, should any undue production of heat take place or nitrous fumes be developed, the supply of air to the injector may be increased and the temperature thus brought down.
In cases where the space available for the apparatus does not admit of the use of a long mixing pipe or "tube," such as is described, the "tube" is carried direct to a tank surrounded by a water-jacket. A pipe leads from this tank, from or near its bottom, back to the mixing chamber or space at the rear of the nozzle of the "chamber." This pipe contains a cock, which, while the atomized acid and glycerine are being mixed, is closed. When a quantity of explosive has been thus made, the acid and glycerine supply pipes are closed and this cock opened. The continued flow of air under pressure produces a rapid flow of the mixture from above pipe back into the collecting tank. The expanding air with its refrigerating effect keeps down the temperature, while by the circulation and agitation the substances are thoroughly and intimately mixed.
An air vent is provided in this collecting tank, and the same disposition as in the previous case may be used for quenching the mixture by jets of water.
The subsequent treatment of the nitroglycerine or other compounds made by this process may be the same as in the case of similar compounds as hitherto manufactured.
What he claims is:
The method or process of manufacturing explosives as described, which consists in separately atomizing or finely dividing the nitrating agent and the material to be acted on thereby, and uniting the two or causing them to intermingle while in such condition.
The continuous process described of manufacturing explosive compounds, which consists in uniting and causing to intermingle jets of the acid and material to be acted on thereby, in the condition of spray, carrying off the spray in a mixing chamber, and collecting the resulting compound in a tank or receiver.
The method or process described, which consists in atomizing or spraying glycerine by a jet of air under pressure, separately atomizing or spraying in a similar manner a nitrating agent, and mixing the two substances while in the condition of spray.
The method or process of manufacturing explosives, which consists in separately atomizing and uniting the spray of the nitrating agent and the substance to be acted on thereby, and then quenching the mixture with water.
The combination of a nozzle, a receiver or source of compressed air connected therewith, a tube or chamber surrounding the nozzle, a tank or receiver for glycerine connected with said chamber, a second chamber, and a tank or receiver for acids connected with the same, the first chamber being formed with a contracted nozzle that enters the second or mixing chamber, the above parts being arranged in substantially the manner as set forth to constitute an injector for atomizing and mixing glycerine and acid.
The combination, with a collecting tank, a mixing tube or chamber leading thereto, and a nozzle or means of quenching with water an explosive mixture delivered from the mixing tube into the collecting tank, of an injector at the end of the mixing tube, tanks for containing acid and glycerine, respectively, connecting with the injector, and a receiver or source of compressed air for operating the injector.
The combination with a receiving tank and mixing tube or chamber, of two concentric injector nozzles, receivers for containing glycerine and acid, respectively, connected to the chambers surrounding the nozzles in the rear of the orifices of the same, and a source of compressed air, as set forth.
In discussing "Precautionary Regulations during the Preparation of Nitroglycerol," F. Scheiding, Zeits.f. angew. Chem., 1890, 609- 613, first suggests that the mixing of the acids should be made in a vessel provided with a cover and chimney for conveying the acid fumes out of the building. The mixing can be effected by means of compressed air, and the cover prevents any of the acids from being thrown out of the vessel. Montejus should be made of cast or wrought iron, preferably not lined with lead. Cast iron withstands the action of the acid better than wrought iron, but is liable sometimes to crack, especially when the air-cock is opened. This cock should therefore be placed outside of the building or separated from the montejus by a wall, and the montejus should stand clear of everything, so that any leak can easily be observed. In the next operation, which properly may be called dangerous, viz. the nitration of the glycerine, rise of temperature which might lead to explosion may be caused by impure glycerine or the accidental admixture of water. The chemical examination of the glycerine is therefore essential.
The nitrating vessel must be made of thick lead and stand clear on all sides in a well lighted building, yet not exposed to the direct rays of the sun. The contents of the nitrating vessel should be kept cool by several separate coils of thick leaden pipe, through which cold water passes. In order to prevent any water from escaping into the acid mixture, should one of the worms be damaged during the operation, the cooling water should flow from a higher lying vessel and discharge into a lower lying tank. The cooling worm would thus act as a siphon and draw some of the acid and nitrogen mixture into the lower tank, where its presence would be recognized by the turbidity produced, or by means of litmus paper. The agitating or stirring is best effected by compressed air, and the workman should always ascertain by means of a manometer whether there is sufficient air pressure before commencing the nitration. In order that no water may be carried over with the air, a condensation box should be fitted at the lowest point of the air pipe. The nitrating vessel must be provided with a cover or hood and chimney, which will convey the acid fumes out through the roof. The whole apparatus should stand over a large tank containing water, into which the whole contents of the nitrating vessel can be promptly discharged through a large earthenware cock, should the temperature rise to 40° C. The floor of this building in certain districts consists of sand, in others of clay. The author prefers a clay floor slightly sloping towards a gutter in the middle which passes underneath the door.
The floor should be kept always damp and covered with sawdust, and the place where the men stand covered with a soft mat. The mat should be washed twice a week, and the sawdust renewed once a week and the removed sweepings burned.
The author suggests the erection of one or two shelter huts, in which one or two workers could take refuge when an explosion threatens, and be protected from falling pieces. An alarm horn should be hung in the shelter hut, by which a warning signal could be given for the whole factory. As explosions have been caused in other buildings by debris falling through the roof, the author advises that the roofs of the buildings in which nitroglycerine or dynamite is present should be provided with a strong double lining. The intervening space would also keep the building cooler in summer and warmer in winter. An electric bell should be near the nitrating apparatus, by which a signal could be sent to the laboratory in the event of anything unusual occurring during the operation. The plug of the discharge cock should be carefully examined before each operation to see that it is quite free from any grit or frozen nitroglycerine.
For conducting the nitroglycerine and waste acids through the mound surrounding the building, a brick channel thickly covered with tar is recommended, just sufficiently wide to take an open leaden gutter, through which a leaden pipe can be pushed. This pipe can be daily cleansed by rinsing first with concentrated sulphuric acid and then with water.
The author considers the combination of the nitrating apparatus with the separator in one building as injudicious. The separator should be provided with a perforated pipe for compressed air, that in the event of heating taking place, which often occurs only at separate spots, the mixture could be agitated and the danger possibly avoided. It should also have electric thermometers which would ring a bell when a certain temperature was reached. The separator should also have a hood with chimney passing through the roof. Outside of the mound surrounding the separator house there should be a pipe for compressed air, with a cock by means of which the agitation of the liquid in the separator could be started, should the workmen have fled from the building on signs of danger without starting the air agitator. Should the bells in connection with the thermometers cease ringing, the building can safely be re-entered. An essential condition of safety is that all the apparatus should be carefully examined daily, to see if it is in proper working order. After the nitroglycerine has passed to the washing house the most dangerous operations are passed. There the greatest cleanliness should be observed and care taken that no wash water, which always contains some nitroglycerine, is splashed about. The nitroglycerine must be washed quite free from acid.
Dr. Thomas Darlington, in treating of "The Effect of the Products of High Explosives, Dynamite and Nitroglycerine, on the Human System," says in the Medical Record 38, 661-662; 1890: When dynamite or nitroglycerine is used in open-cut work, as on our railroads, after the explosion the gases immediately distribute themselves in the atmospheric air, and no effect has been noticed on the workmen employed. But when used in tunnels, as in mining or other partially closed cavities, where the gases or residues are slow to escape from the mouths of the tunnel, or up air shafts, serious deleterious effects are produced.
There are, for purposes of study, practically two classes of dynamite, which might be termed inorganic and organic, according to the absorbent used. A type of one class is that made with infusorial earth, and of the other, that made with wood pulp or sawdust. Others still are made from a combination of both. The results of the explosion, however, are practically the same in either case, except that with the organic absorbent we get with the products an additional amount of carbon.
An experience of over five years where such explosives have been in use has led me to believe that an article on this subject might be of interest to some of the medical profession.
During 1885 to 1887, while surgeon to the New Croton Aqueduct, fully thirteen hundred cases of asphyxia, or partial asphyxia, and poisoning, from the products produced by the explosion of dynamite, came under my care; and more recently a few other cases which I have had better opportunity to study.
Two classes of cases were observed: First, where a considerable quantity of the products was inhaled at one time—acute cases; second, where the men constantly breathed a small amount, or chronic cases. The acute cases varied according to the amount inhaled.
In some cases where the amount of dynamite used was not large, or where, after the explosion, a considerable quantity of fresh air has been mixed with products of combustion, or where the workman has after a few breaths become giddy and is pulled away by others and sent to the surface, the effects produced are a trembling sensation, flushing of the face, succeeded sometimes by pallor, frequently nausea, sometimes vomiting, with throbbing through the temples and fullness in the head as if it would burst, followed by an intense headache characteristic of poisoning by nitrites—similar to that of nitrite of amyl, only not so violent, but more persistent, frequently lasting forty-eight hours. The heart's action is increased, and the pulse full and round, though somewhat compressible.
Case I.—J. C., occupation miner, while returning to work after a blast, became dizzy, and crawled on hands and knees back to the bucket; felt as if drunk. About twenty minutes afterward was nauseated and vomited slightly. Had a feeling as if his head was swelled. After vomiting the headache increased. The pulse at this time was full and bounding and 108. Ten hours afterward the headache was more pronounced, and the pulse 88 and more compressible.
Where, however, a man goes into the tunnel immediately after the explosion, and is brought in contact with a large percentage of the poisonous materials, the effects are giddiness immediately followed by unconsciousness, and the patient presents the usual appearance of asphyxia. Sometimes in these cases the pulse is full and bounding, though very compressible; but in most of the cases it is alarmingly weak. Generally there is great pallor, though this may be partially due to working underground. The comatose condition soon passes away, and is succeeded by drowsiness, languor, cold perspiration, intermittent pulse, and generally nausea and vomiting. Sometimes the breathing is spasmodic, and frequently there is hiccough, and after a time a severe headache.
Nearly all of these cases, however, no matter how serious they seem at the time, recover; though a substitute on the Aqueduct, during my absence, was on one occasion so unfortunate as to lose two cases. I found upon inquiry that death in these cases occurred several hours after the patients were removed from the tunnel, and was due to paralysis of respiration.
In the chronic cases there are four prominent symptoms: Headache, cough, indigestion, and disturbances of the nervous system.
The cough is similar in character to the cough of pertussis or of malaria, and at first I was under the impression that it was purely malarial, as cases of intermittent fever were frequent. But although some of the cases may have been complicated with malaria, there were many others that were not, in which the cough was persistent.
In nearly all of the cases there was a continuing headache.
Next in prominence to these symptoms come disturbances of the nervous system, as trembling, irritability, neuralgia, etc. In fact, nearly if not all of the symptoms were attributable to this cause. Even the cough, in all probability, was due to the effect produced on the pneumogastric nerve.
One of the superintendents became so nervous and irritable, largely from this cause, that it was with difficulty that he could get along with the men. All of the men affected seemed extremely nervous. And with this was associated indigestion, probably due to the same cause. Of course, with this latter symptom, the character of the food and the manner in which it was eaten must be taken into consideration. But as soon as a man with these chronic symptoms was taken from the tunnel and placed at work on top, he steadily improved, and would finally recover entirely.
It was also noticeable that those who had previously suffered from dyspepsia or neuralgia were made much worse by the dynamite smoke.
One inspector on the Aqueduct was forced to resign by reason of the constant return of an old "tic douloureux," due to this cause. What were the symptoms recognized due to?
The formula for nitroglycerine is C3H5(N03)3. And the products from the combustion of this are written:
4C3H5N3O9=10H2O + 12CO2+6N2O2.
In other words, the products are water, carbonic acid gas, and nitrogen dioxide; none of which would produce the symptoms above described except asphyxia, but not the effect on the heart, nor the other symptoms witnessed. What then was the cause?
A comparison of the above symptoms in the acute cases with the phenomena produced by various sized doses of nitroglycerine shows them to be identical. This similarity of symptoms from inhalation of the products of the explosion of dynamite, and of those produced by the nitroglycerine itself, is so well marked that even miners themselves have noticed it. Frequently, when dynamite is frozen, a miner will place a cartridge in his boot to thaw it out; and the absorption of nitroglycerine through the skin will produce precisely the same symptoms as in the mild acute cases of the inhalation of the products before described.
Again, I know an instance of where a miner used his knife to cut a cartridge, and afterward cut and ate an apple with the same knife. In this case, according to his statement, the symptoms were similar to being "knocked out by powder smoke," only more severe. The headache persisted three weeks. And on another occasion this same miner cut up some tobacco to smoke, with a knife that he had used for dynamite, and was again similarly affected. Here the heat from the tobacco inhaled smoke volatilized the fine particles of nitroglycerine on the tobacco below, and poisoning was produced by absorption through the lung tissue.
No other conclusion can well be reached than the fact that there is mixed with the gases produced, unexploded particles of nitroglycerine in a volatile state, and these particles inhaled by the miners produced the effect described.
There is no doubt but that the explosion of a large quantity of dynamite would produce sufficient gases of CO2 and N2O2 to produce asphyxia. Here we get the cyanosis and other symptoms of simple asphyxia, and we may get nausea and vomiting; but not the same disturbance of the sympathetic system, nor the continued chronic spasms of the vagus, nor the persistent headache pathognomic of nitroglycerine poisoning. This fact can be conclusively proved by waving in the fumes, immediately after an explosion, a cold sheet of glass, and thus collecting upon it by condensation a small percentage of the nitroglycerine itself.
As regards treatment, as a preventative, the use of such apparatus or machinery, whether by blowing or by sucking, as will rapidly clear the tunnel or cavity from noxious gases or fumes is to be recommended. Where steam drills that are worked with an air compressor are used, they contribute largely to this end.
Also it has been found by makers of dynamite that the use of a large cap will explode a greater percentage of the glonoine than a small one, and this, to a certain extent, obviates the trouble. In certain cases, however, for some reason, a cartridge does not explode, but burns like a candle, with considerable sputtering. In such an instance the amount of nitroglycerine volatilized is much greater than if exploded, and consequently the effects far more deleterious. I have witnessed a whole "shift" "knocked out" from this cause.
Of course, such measures as are generally used in cases of asphyxia are of service. But in addition to these, the use of cold to the head, and of atropine, ergotine, or other vasomotor stimulants, administered subcutaneously, are of necessity indicated and exceedingly efficacious. There is little doubt that the effects of nitroglycerine are produced from its decomposition and the formation of a nitrite in the body, "Treatment with ammonia restores normal color and normal functional power to nitrite-poisoned blood."
Acting on this principle, and from its stimulant properties, I have uniformly treated my cases with inhalation of ammonia, and also given the carbonate and aromatic spirits of ammonia internally; and up to the present time have not lost a case.
It seems to me it would be well for those in charge of such works to recommend to the workmen to carry with them small vials of this remedy for use in similar cases.
In none of the cases did I notice any changes in the blood—that is, darkening—such as are mentioned in nitroglycerine poisoning, but this may have been due to lack of proper observations on my part. In numerous cases of pneumonia the sputum was darker than usual, but this I attributed to the dust and lamp-smoke inhaled.
According to W. Schuckher's English Patent 45,625, Sept. 16, 1890, for "A Process and Apparatus for the Manufacture of Nitrated Starch," starch, preferably potato starch, is dried at 100° C. and finely ground. It is then dissolved at 20°-25° C. in nitric acid of 1.501 sp. gr., using 10 kilos, of acid to 1 kilo, of starch. The solution is added to a mixture of nitric and sulphuric acids, which, for sake of cheapness, may be the waste acid from nitroglycerine manufacture, containing about 70 per cent of sulphuric and about 10 per cent of nitric acids. Five kilos, of this waste acid are employed to every kilo, of the nitrated starch solution, the mixture being kept at a temperature of 20°-25° C. Nitrated starch is precipitated as a fine powder and is collected on a filter of gun-cotton. The bulk of the acid is then removed from the precipitate by hydraulic pressure. The cakes produced are well washed in water and treated with 5-per cent soda solution. After 24 hours the cakes are ground between rollers, the creamy mass formed being afterwards dried by means of a centrifugal machine or a filter press. Finally about 1 per cent of aniline is added to the residue, which still contains 33 per cent of water. Nitrated starch as prepared dissolves readily in nitroglycerine. In the cold it forms at first a mass resembling lime, but as more of the nitrated starch is added a hard waxy material is produced.
A very serious accident occurred on the 13th May in a factory at Avigliana, during the manufacture of ballistite, by which 13 lives were lost. Through the Foreign Office we have obtained some interesting particulars of the accident, collected by Col. Slade, British Military Attaché at Rome. It appears that "The factory, or rather the special portion of the scene of the occurrence, is a long-roofed structure, divided into five separate compartments, where the operations of milling, cutting, sifting and cleaning are carried out.
"In the first ward the ballistite, by means of a special engine, is prepared in the form of sheets, after being laid in a wooden trough fitted with double zinc plates, and subjected to the heating process by means of hot-water pipes, after which they pass to the cutting machine.
"The second ward was empty at the time of the fire, a large platform being in course of construction for the setting up of two cutting and two grinding machines.
"In the third were several cutting and granulating machines, together with a ton of smokeless powder ready prepared to be despatched to the navy.
"The fourth contained the sifting machine, and it is also supposed that upwards of two or three tons of black powder were also in the ward.
"The cleansing machine and upwards of four tons of black powder, partly packed and partly loose, were in the fifth compartment.
"All the several compartments are connected by vaulted passages, and all have an outlet by means of light glass doors; all these doors were open when the fire broke out.
"A workman, who was standing about 70 yards off", stated that the fire broke out in the first compartment, and spread with the greatest rapidity through the other four. No dead body was found in the first ward, two were found in the fourth, and eleven crowded together at the door of the last; among these eleven were the remains of a man who at the time was working in the first compartment.
"This leads one to fairly assume that the fire originated in the first compartment, either through the action of the cutting machine, or by the sudden ignition of one of the strips of ballistite through overheating.
"The bodies of the five men working in this ward were set on fire, and the poor fellows, in place of running out through the open door, fatally searched for an escape through the several compartments, thus spreading fire in every direction, to the last room, where the heat must have reached such an intensity as to have produced immediate death. All the tools and wooden implements were slightly charred, whilst the metal of those zinc-plated had completely melted away.
"The various machines did not suffer much from the results of the accident, and will be set at work again as soon as the buildings have been repaired.
"One of the walls of one of the wards was blown down and three were unroofed, the tiles falling outward. The first two wards were left almost intact. The total amount of powder destroyed may be reckoned at about 8 tons, whilst the damage is estimated at about 4000 l."
Although nothing definite is disclosed as to the cause of the accident, there can be no doubt that the manufacture was being carried on in a very dangerous manner, with a wholly unnecessary accumulation of persons and explosive material within a single building, and with a very inexcusable neglect of what in this country would be regarded as essential precautions.
It is most important (especially when dealing with a comparatively new material like ballistite) to isolate the various processes, to subdivide the amounts of material so as to limit the effects of a possible accident, and to allow only a very few work-people within a single building or risk.
None of these things were done here, and the subdivision of the buildings into wards (as the event showed) was entirely illusory.
It has been suggested (by the Italian Director-General of Artillery) that a piece of ballistite in being carried from one machine to another may have fallen off one of the trays, and that some small grit or gravel may have adhered to it, and so brought about the explosion, when the machinery was again set in motion. This suggestion is not intrinsically improbable, but if it be accepted it would point to an even greater disregard of precautions, because one of the first efforts of the maker of explosives should be directed to the rigid exclusion of grit from danger buildings.
The one satisfactory point in connection with this accident (which in its consequences, if not in its inception, would appear to have been entirely preventable), is, that although no less than about 8 tons of ballistite is estimated to have been consumed, there was no violent explosion. This observation usefully supplements the results obtained in the experiments with burning the kindred explosive "cordite," which are described in the Experiment Section of this Report.—15th Ann. Rept. H. M. Insp. Exp. pp. 49-50; 1891.
According to O. Guttmann, Ding. Poly. Journ. 278, 25; 1890, smokeless powders have been the cause of fatal accidents at Spandau as well as at Avigliana, which are believed to have resulted from the fact that the behavior of these bodies, under all conditions of production and with novel machines, is yet but imperfectly known.
Among the accidents by fire or explosion which have come under the notice of the Home Office from January 1 to December 31, 1890, we note the following due to ballistite:
The first occurred Feb. 27, at Factory No. 3, Ardeer, Ayr (Nobel's Explosive Co., Limited):—A small "crack" occurred in the ballistite when between the rollers. The foreman felt as if something had struck his wrist, and a mark was found like the prick of a pin. Whether this was a particle of dry nitro-cotton or minute fragment of iron is unknown. The mark in the sheet of ballistite was as if made by a pin point. No one was killed or injured.
The second occurred at the same factory on March 20:—A sheet of ballistite "cracked" in rolling and was broken, but no damage was done. No one was killed or injured.
The third occurred at the same factory on May 13:—A small quantity of ballistite which was being rolled between steam heated rollers, took fire. No one was injured, and no damage was done.
The fourth occurred at the same factory on May 28:—About an ounce of ballistite exploded in an experimental screw-press, about a pound of finished ballistite being ignited by the explosion. No one was injured, and very trifling damage was done to the machine.
The fifth occurred at the same factory on June 21:—Breech-block of sporting gun slightly cracked in experimenting with smokeless sporting powder. No one was injured. The accident was due to the detonation of the ballistite charge on firing with an ordinary percussion primer.—15 Arm. Rept. H. M. Insp. Exp. pp. 1 15-143;
In his "Novelties in the Explosives Industry and Blasting," Ding. Poly. Journ. 275, III; 1890, Oscar Guttmann says since our last installment the problem of smoke-weak powders has undergone a more rapid development than has ever before been known in the history of explosive agents. The daily papers teem with surprising statements wherein powders of unlike characters are classed in one category, so that it is difficult even for an expert to determine precisely what is meant. Under these circumstances it is the province of a technical paper to give its readers an accurate and extended account of the subject, but unfortunately the restrictions in this instance are of such a nature that only a general picture of the fundamental principles can be given.
It is but a short time since the adoption of magazine and rapid-fire guns was a burning question, and in a certain sense it is yet an open one, but still the powers have equipped their armies with rifles of one-third less caliber than those formerly in use, in order that the already heavily burdened soldier may carry a greater number of rounds of ammunition. This change in caliber necessitated, from the outset, a change in the powder charge, for it was essential that the bullet should have an equal range. Next, as owing to the rapid fire but little time was allowed for aiming the piece, it became essential that the projectile should have a very flat trajectory. This pointed to the use of a very brisant powder; but as this would necessitate the use of a very strong piece to resist successfully the suddenly developed pressure, it was agreed that new powder must be less brisant and should develop its full power at the muzzle of the piece, giving a high initial velocity with a low pressure.
These conditions obtain equally for small arms as for great guns, but the further development for the two classes is different and the powder problem becomes unlike for the two. Hence, when speaking to-day of the smoke-weak powders we refer principally to the small-arm powder.
Although at the outset it was sought to satisfy these requirements by changes in the composition, method of treatment during manufacture, and in the form of the cartridge, a fresh difficulty was soon encountered. Even before this "an atmosphere filled with powder smoke" had been no empty phrase, but with the rapid-fire guns it was found that the smoke would be increased so as to be insupportable, and that even the skirmisher would be so enveloped, after a few rounds, especially in calm weather, he would be unable to take aim. Hence a powder had to be invented which burned without smoke, and since this, while theoretically possible, was not so in practice, the powders of this class which appeared were first styled in Germany smoke-feeble powders (rauchschwaches Pulver).
From the preceding it appears that the smoke-feeble powder should satisfy the following requirements:
- High power in a small space.
- Low specific gravity (to produce a light cartridge).
- Low gas pressure.
- High initial velocity.
- Great flatness of trajectory.
- Small development of smoke.
- Harmlessness of the smoke.
- Constancy.
- Safety in handling.
The eighth point demands a thorough discussion, for under "constancy" is to be understood a number of conditions.
We shall see later on that the smoke-weak powders principally belong to the class erroneously styled chemical explosives. The readiness with which such substances are resolved by explosion into their constituents throws a doubt on their constancy under all conditions, and their permanency must be proven under all the extremes of heat and cold, dampness and dryness, blows and shocks, agitation, exposure and the like, which obtain in practice. Again, the tendency, such as has been observed in the black powder, to separate into its constituents when moist must be provided against. No mildew should form upon them as does form on gun-cotton. They should have no action on the walls of the cartridge cases. They should be so insensitive to mechanical influences that they will withstand careless handling in the field.
In seeking for the ideal smoke-feeble powder it was but natural to turn to nitrocellulose. Already for many years wood nitrocellulose, known as Schultze powder, has been employed in England for sporting purposes, and this was followed by E.C. powder, which consisted principally of gun-cotton; while more recently a number of other gun-cotton powders have been noticed, principally for use as sporting powders, but were introduced into use only with great difficulty, and the sporting-paper Field had frequently to recount accidents caused through the bursting of the pieces.
Owing to the increasing use of gun-cotton for filling torpedoes and shell, the process of manufacture has been so perfected as to yield an explosive whose properties can be maintained nearly uniform. At the same time, owing to melinite, attention has been called to picric acid and its derivatives, and these have been more thoroughly studied.
The use of gun-cotton proper (trinitrocellulose) could not be thought of, owing to the brisant action of this body, but it was found that collodion-wool (dinitrocellulose, soluble gun-cotton), which was less brisant, could be converted into a nearly homogeneous mass which satisfied many of the requirements of a smoke-feeble powder, but it was still so brisant when used alone as to produce too high gas pressures and too irregular initial velocities. Hence the more successful recent powders consist of soluble gun-cotton mixed with other substances which diminish the brisant effect, or it is treated in a particular manner to produce the same result. Thus Wolff & Co., in Walsrode, who have been treating gun-cotton for use in shell charges in a similar manner, treat the collodion-wool with acetic ether, and the thin skin of collodion thus produced retards the rate of burning. A similar process is employed by H.S. Maxim, of London who conducts the vapor of acetic ether to the gun-cotton, and when action has taken place, forces the plastic mass through holes into strips, which are then cut into smaller pieces.
Fr. Gaens, in Hamburg (under which name some expect to find the powders produced by the Rottweil-Hamburg factory), dissolves nitrocellulose in acetic ether to form a gelatinous mass, and mixes with 25 parts of the nitrocellulose, 60 parts of potassium nitrate, and 15 parts of ammonium hum.ate (obtained by treating peat with lye); the mixture being then pressed, granulated and dried.
The Nobel smoke-feeble powder was originally a modification of the camphorated blasting gelatine, but it was found that the camphor was unreliable and required a special purification to secure uniform results. At present, according to private information, this powder consists of 50 parts of nitroglycerine and 50 parts of collodion-wool. It is impossible to produce a gelatine containing so large an amount of nitrocellulose directly, so benzol, in the required proportions, is mixed with the nitroglycerine, and these are sprayed in fine streams on the nitrocellulose. The mixture, after evaporation of the benzol, is then rolled into sheets which are cut into strips and grains. The sheets have a dark brown color and resemble caoutchouc. The powder is more yellow-brown. If a sheet is ignited it burns in layers and emits sparks.
It is interesting to note that in the case of the Nobel powder, nitroglycerine, which is one of the most powerful explosives, is used mainly to diminish the brisant effect of the collodion-wool, and also that it does not detonate even under the influence of the primer of the rifle. The impediments which prevented the production of perfectly uniform gelatine are inherent in the manufacture of this powder, and this lack of reliability is no doubt the reason why this smoke feeble powder, which otherwise possesses so many excellent qualities, has not come into use.
Abel and Dewar are reported to be engaged in perfecting the gelatinization process for the English government, and in manufacturing a powder which is said to have given excellent results. This new powder, called Cordite, is brown in color, and is in the form of cords of the length of the cartridge, which are bundled like fagots.
The Swiss government have already introduced a smokeless powder, P. C. 88 (Powder Composition 88), made by Schenker and Amsler Sohn, which gave with a charge of 2.4 grams in the 7.5 mm. Schmidt rifle an initial velocity of 615 m., with a maximum pressure of 1300 atmospheres.
France has for some time possessed the smokeless powder produced from collodion-wool by Vieille. Austro-Hungary seems recently to favor the powder of Major Schwab, which is described as a dark-gray, coarse-grained chemical product. Belgium is engaged in the production of wood-nitrocellulose. Germany, which has perhaps made the largest number of trials of private powders, is said to have declined to accept any powders produced by private firms, and to have recently rejected a large lot for failing to meet the requirements and for lack of sufficient stability. It is believed that Germany possesses in the powder manufactured by Major-Gen. Kuster, at Spandau, an excellent shooting agent.
In general it may be said that no perfect smoke-feeble powder has yet been invented, each of those known having its weak points, and therefore those governments that are not directly menaced are disposed to await further developments.
Picric acid and its congeners play an important role in cannon powder. It is yet too early to treat of this, because very sensible irregularities are observed in the composition for large charges, and up to the present nothing really good is at hand. In general, guncotton, ammonium picrate and fused picric acid are preferred for projecting and bursting charges.
Since the patents of the different factories seem to conflict, and the different smokeless powders have much in common, some of the German manufacturers have combined with Nobel, by which all are protected, and through their co-operation one satisfactory powder may be obtained.
In the Journal of the Royal United Service Institution, London, July, 1891, p. 707, is a paper by Lt. Col. G. V. Fosbery, in which, after referring to the historical development of the magazine gun, he continues as follows in regard to the ammunition which they carry: "Side by side with the change of weapons, a no less important one has been made in the ammunition they carry. That such should have been the case is but the logical consequence of the adoption of the repeater. From the moment this was decided on, it was seen that, in the first place, it would be desirable to reduce the size of the cartridge so as to maintain the handiness of the weapon; and, secondly, to reduce its weight in order that the soldier might carry a larger number—wrongly or rightly supposed to have become an absolute necessity.
"To reduce the size of the cartridge, the space occupied by the charge must be diminished, and for this either the present charge must be made to occupy a smaller space, or a more energetic explosive be found. We are thus at once compelled to use either compressed gunpowder, or one of the higher explosives.
"Again, to take largely from the weight, the bullet must be lightened; and here we must be careful. The range of artillery is increasing every day, and the bringing of quick-firing guns into the field is but a question of time. The infantry cannot afford to lose a yard of their range. The sectional density of the bullet cannot, therefore, be lowered—nay, rather needs increasing—and the reduction in weight must be effected by a diminution of caliber.
"Many of us were in hope that this would go no further than to 0.400 inch or 0.380 inch, when a plain hardened bullet could have been used, and a very considerable economy in the price of ammunition been effected. When, however, it came to be seen what velocities, range, and penetration could be got with a thing like this, no bigger than a common pencil-case, the caliber of 0.303 was decided on, and with it, as a consequence, the metal envelope, regarding the cost and other difficulties of which so much has been said. The Studies of Hebeler and Guillaumot, and the practical experiments of Lorentz prepared the way for this or even a greater reduction of caliber; so that, in theory, no risks of mistake were run.
"It may be an open question whether or no at extreme ranges the fire of the new magazine gun will be as fatal as is that of the Martini-Henry, and whether it would be possible with it to inflict on a distant enemy such terrible losses as fell upon the Russian columns in the valleys near Plevna from Turkish un-aimed high-angle fire. We all know that a very small and light bullet, having a speed of 1600 feet per second or over, i.e. a bullet traveling at so-called express speed, will smash bones and tear up and pulverize flesh in a way totally different from the behavior of the same bullet endowed with a lower velocity, and it may prove to be the case that beyond certain ranges, the effects of the new projectile, say on supports and reserves, will be less than those of the heavy Martini bullet in a very notable degree. As, however, we are promised an initial velocity of something approaching 2000 feet per second, no doubt we shall have an extremely flat trajectory and deadly effects for a very considerable distance, and in any case what is true of our own bullet will—so nearly alike are they—be true of every other bullet in Europe.
"At present, so far as is known to me, we are still in search of the ideal explosive; one, in fact, which shall pack into the smallest possible space, develop the utmost energy, and keep indefinitely under all possible circumstances, and until we have found this, or at all events some reasonable approach to it, we cannot with a light heart adopt, as our Continental friends have done, a smokeless powder for the use of our troops. Gunpowder we know all about; it is a good honest mixture, and, sorely tried as it frequently is ashore and afloat, it may be always reckoned on to do its duty so long as we keep it dry. But when we come to high explosives—specially when these are chemical compounds, and from their very nature more or less unstable compounds at that—we, more than any other people, must exercise the utmost precaution in their general adoption, and be sure that neither the damps and heats of India, the salt air in our naval magazines, nor the cold of Canadian winters, will set these treacherous substances fermenting, decomposing, or exploding. Hitherto perhaps on the whole Professor Abel's powder, cordite, has shown the best all-round qualities, and bids fair for final selection.
"Having thus spoken of the ammunition question, which will, I believe, when fully settled, effect a more marked change in the conditions of war than even the adoption of the magazine gun, I will, if you please, return to the question of the latter."
U. S. Letters Patent No. 456,508, July 21, 1891, have been granted Alfred Nobel for an Improved Celluloidal Explosive and Process of Making the Same.
It is known that the gelatinous compound commonly called "blasting gelatine," and patented by him in 1876, is composed of nitroglycerine and soluble nitrocellulose, the proportions adopted in practical use being from five to seven parts by weight of the nitrocellulose, to from ninety-three to ninety-seven parts of nitroglycerine, to which is added a small portion of nitro-benzol or analogous matter when it is desirable to make said jelly less sensitive to concussion or percussion. This compound, owing to its eminently detonative character, has been extensively used for blasting rock, but has proved altogether too violent in its action for use as a propeller for projectiles.
The object of the present invention is to so modify the explosive character of this compound as to produce from the same materials an essentially new article possessing the progressive explosiveness needed for propelling projectiles. This he effects by employing a process enabling him to incorporate with nitroglycerine a quantity of soluble nitrated cellulose 10 to 20 times greater than that which is contained in his "blasting gelatine," thereby producing a substance which, in its physical aspect as well as in its intrinsic explosive properties, differs widely from the "blasting gelatine," inasmuch as through the horny or celluloidal character which it assumes it is capable of being reduced to so-called "grains" akin to those of granulated gunpowder.
In manufacturing his present explosive, he dissolves in 100 parts, "by weight, of nitroglycerine, say 10 to 15 parts, by weight, of camphor, adding thereto as a diluent, say 50 to 100 parts, by weight, of benzol. To this mixture is added, say 100 parts by weight, of dried, pulped, carded, soluble, nitrated cellulose, such as nitrated cotton fiber. He then mixes the materials until the nitrocellulose has completely absorbed in its pores the aforesaid liquid and until homogeneity is secured. This done, the benzol is evaporated in the open air, or, better, in a closed chamber provided with a cooled condenser, for the purpose of recovering the benzol or the greater part thereof. When the benzol is evaporated, the material thus obtained is passed for malaxation between steam-heated rollers, when it assumes the aspect and consistence of a somewhat soft celluloid. It is then ready to be rolled out into sheets of any required thickness. These sheets he converts into "grains" by cutting them up into cubes or small pieces of any desired shape, which reduction serves the same purpose as granulation for gunpowder.
The addition of benzol, for which may be substituted any other volatile substance having the same property of mixing with nitroglycerine and rendering nitrocellulose insoluble therein, serves no other purpose than to facilitate by such insolubility the equal absorption and distribution of the liquid into the fibers of the nitrocellulose. As soon as the benzol has been evaporated the nitrocellulose begins to dissolve, and when dissolved the compound is treated as already described.
The given proportions of the ingredients are not absolute, but may be varied in a wide measure, the limits of which will be determined by the facility or resistance which the compound offers to its reduction into "grains." Thus if the celluloidal substance contains more that 2 parts of nitroglycerine to 1 part of nitrocellulose, it becomes almost too soft for a substance which has to be used in a granular form; and if it contains as little as 1 part of nitroglycerine to 2 parts of nitrocellulose, the celluloid obtained is more stiff and hard than needed, and is less easy to manufacture than such celluloid containing no more than half its weight of nitrocellulose.
When the celluloidal substance is made to contain more than half its weight of dissolved nitrated cotton fiber, its formation in the manner described becomes somewhat troublesome, in so far as it requires a prolonged malaxation between steam-heated rollers, or similar treatment. In such case he prefers the substitution for benzol of a volatile substance, such as acetate of amyl, or of ethyl or acetone, wherein the nitrocellulose is soluble, and wherewith the nitroglycerine is miscible, and he adds of such solvent the quantity needed for complete incorporation of the ingredients; the proportion depending on the solvent's volatility and the temperature at which the malaxation is effected; but there is no mistaking in practice the proportion needed, since sufficient of the solvent must be added to obtain a translucent celluloidal substance. Moreover, for practical use the above given proportions of equal parts of nitrocellulose and nitroglycerine plus camphor gave an excellent result, so that the addition referred to of an excess of nitrocellulose, necessitating an extra addition of solvents, will be resorted to only in exceptional cases.
The nitrated ingredients used are to be deprived carefully of adhering acids by proper methods of washing.
Solid powdered substances may be kneaded in by malaxation between steam-heated rollers or otherwise, and the explosive celluloid may be mixed with pulverulent explosives, such as nitrated starch, nitrated dextrine, mealed gunpowder, or picrates; but it may also be mixed, and this is of importance with powdered oxidizers, such as nitrates or chlorates, for the purpose of furnishing the oxygen wanting for complete combustion, and with a view to reduce the cost price of the article.
The celluloidal explosive composed of 100 parts of, nitroglycerine, 100 parts of nitrocellulose, and 15 parts of camphor, contains approximately the oxygen needed to convert, by explosive combustion, all its constituent hydrogen into water vapor and all its carbon into carbonic oxide; but to obtain complete combustion and thereby to convert said carbonic oxide into carbonic acid, it would be necessary to incorporate with each 100 parts of the compound about 82 parts of nitrate or chlorate of potash, or 69 parts of nitrate of soda, or 100 parts of nitrate of baryta, or 163 parts of nitrate of ammonia, or 96 parts of perchlorate of ammonia.
Bearing in mind that one part of hydrogen requires for its combustion eight parts of available oxygen, and that each six parts of carbon require for transformation into carbonic oxide eight parts, and for forming carbonic acid sixteen parts of available oxygen, it is easy to calculate the proportions of oxidizing nitrates or chlorates suitable for each particular case, it being understood that the quantity of oxidizers added should not exceed that needed for complete combustion. Also, the quantity of powdered oxidizers which can be added is limited by the capability of easy practical incorporation by malaxation. The more nitroglycerine and the less nitrocellulose it contains, the more soft and plastic the explosive celluloid becomes, especially when heated, and the greater will be the proportion of powdered substances which can be practically incorporated.
The camphor or other predisposing solvent may be partly, and even almost entirely evaporated without very materially altering the explosive properties. Such evaporation can be effected by long exposure to the air at the ordinary temperature; but it is much quickened by letting a current of air heated to, say 50°C, percolate among the "grains" of the powder. Of course such evaporation reduces the amount of carbon and hydrogen, so that if oxidizing nitrates or chlorates be incorporated with the explosive, their quantity should be proportionately reduced.
This explosive celluloid can be used for blasting rock, in which case the "grains" maybe compressed, similarly to gunpowder, so as to form cylinders or pellets suited for miners' use. Such compression may either be effected at a temperature (60° to 80° C.) at which the material becomes sticky, or at the ordinary temperature by slightly moistening the grains with a solvent, such as acetone or an acetic ether. Of course the grains should not be compressed so much as to leave no air space, upon which the quick spreading of the flame depends. The aforesaid powder can be fired without a detonator, thereby completely differing from the so-called "high explosives" now in use.
Whether for blasting or propelling purposes this explosive has always to be used in a granulated state, or so divided as to present a sufficiently large surface for combustion. The size of the grains or particles varies for each caliber of arms and other varied conditions, as is likewise the case with gunpowder; but otherwise the mode of using and firing does not materially differ from that explosive, except as regards suiting the charge to the ratio of power.
He claims:
1. A process for forming hard celluloidal explosives for propelling or filling projectiles, or for blasting purposes, which consists in uniting nitrocellulose and nitroglycerine, in proportions substantially as set forth, by means of a volatile solvent, as acetone, camphor, or the like, and subsequently removing said solvent, and mechanically treating the same, substantially as specified.
2. The hard, horny, or celluloidal explosive in granular form for above purposes, containing nitrocellulose and nitroglycerine, the same being so far solid at ordinary temperatures as to be susceptible of being cut up into so-called "grains."
3. The celluloidal explosive above described, in dense, horny, granular form, solid at ordinary temperatures, composed of nitrocellulose, nitroglycerine, and suitable oxidants, as specified, and adapted for propelling or filling projectiles, or for blasting purposes.
The following "Experiments to Determine the Liability of Cordite to Explode en masse'' were carried out on Woolwich marshes on the 21st of October, 1890, by the War Office Chemical Committee on Explosives, in the presence of the Director General of Ordnance Factories, H. M. Chief Inspector of Explosives, and other officers.
1. 100 lbs. of coarse cordite (3 in. diameter and 14 in. in length), packed in a service box (measuring 2 ft. 3 in. X 14 ft. 6 in. X 7 ft. 9 in. deep, and having 1 ¼ in. sides and 1 in. top and bottom), was attempted to be ignited by means of a tube and small priming charge of gun-cotton. But the cordite failed to ignite.
2. Repetition of above, but using a small priming charge of fine cordite (.05 in. diameter and 11 in. long). The whole mass burst immediately into flame, and burned with great and rapid energy and brilliancy. The lid was removed by the energy of the outburst, the screws being drawn, and those on one end bent. The mass burned for about three seconds, and the light was of the most brilliant character.
3. Repetition of No. 1, and with same result. No ignition.
4. Repetition of No. 2. The cordite ignited and burned with great brilliancy and a gush of bright flame for about 7 ½ seconds. The lid of the box was forced off (as in No. 2), and the screws were drawn, and in some cases bent.
5. A service case (of dimensions previously given) containing 100 lbs. of the fine cordite was surrounded by wood and shavings, which were set fire to. The bonfire burned for 15 minutes, when the cordite in the case ignited and burned, with a great rush of most brilliant flame, for about four or five seconds. Some small pieces of the burnt wood were then thrown to a distance of about 12 yards. An end of the box was forced out. One side was partially forced out.
6. Repetition of No. 5, but using fine instead of coarse cordite. After the bonfire had been burning for seven minutes the cordite caught and went off with a dull, muffled burst which nearly amounted to a mild explosion. There was, however, certainly nothing approaching a violent explosion, as was shown by only one side of the box being displaced.
7. Six service boxes containing each 100 lbs. of thick cordite were placed together, five on end and one on the top; the center box (in lower tier) was set fire to. It burned about six seconds, and upset the side boxes, but it did not throw off the top box; only the box which was ignited caught fire.
8. Five service boxes each containing 100 lbs. of thick cordite (i.e., those which remained from the last experiment) were placed in a pile, two, two and one, breaking joint; and surrounded by wood and shavings, which were set fire to.
After 15 minutes, 1 box of cordite ignited.
After 15 minutes, 7 seconds, 1 box of cordite ignited.
After 15 minutes, 14 seconds, 1 box of cordite ignited.
After 15 minutes, 21 seconds, 1 box of cordite ignited.
After 15 minutes, 28 seconds, 1 box of cordite ignited.
Each box burned with a bright rush and burst of flame, but without explosion. The boxes were not broken up, and no fragments of the bonfire were projected beyond about 10 paces.
9. A pile of eight service boxes containing each about 75 lbs. (total 600 lbs.) of cordite was surrounded with wood and shavings, which were set fire to. The top box had a hole in it, which was roughly plugged, and this apparently caught fire and burned away non-explosively at 1 min. 10 sees, after the bonfire had been ignited. The other boxes ignited in succession and burned away non-explosively.
C. Roth, Eng., Pat. 858, Jan. 16, 1890, for “Improvements in the Manufacture or Separation of Ammonium Nitrate and Sulphate or Chloride of Sodium and of Potassium,” prepares ammonium nitrate from equivalent quantities of ammonium sulphate and potassium or sodium nitrate, either by heating the aqueous solution of these salts or by melting them at a temperature below that at which ammonium nitrate dissociates. If the aqueous solution be heated to a temperature above 110°C until practically all the water is driven off (110°C being the temperature at which a solution of ammonium nitrate in an equal weight of water boils), or when the salts are heated in the absence of water and the melt maintained at a temperature between 160° and 200° C, sulphate of potassium or sodium, as the case maybe, separates out in the solid form and settles to the bottom of the melt, whilst a liquid layer of ammonium nitrate remains above, which can be easily siphoned off or otherwise removed. A solution of ammonium in an equal weight of water, at a temperature of 110° C, is only capable of holding in solution 15 per cent of sodium sulphate and 10 per cent of potassium sulphate, and the solubility of these substances in ammonium nitrate decreases as the temperature is raised, until at 200° C. (at about which temperature ammonium nitrate decomposes) only traces are held in solution. Ammonium chloride may be similarly used instead of ammonium sulphate, but its greater cost makes it less advantageous.
C. Roth and W.J. Orsman, Eng. Pat. 20,104, Dec. 13, 1889, for "Improvements in the Treatment or Preparation of Nitrate of Ammonium," proceed as follows: To prevent the absorption of hygroscopic moisture by ammonium nitrate, the crystals of that salt are dried by heating to 80° C, and a solution of nitrocellulose "in the various nitro- and chloro-nitro compounds of benzene or of the benzene series of hydrocarbons and their derivatives" is then poured over them, the mixture thoroughly stirred and allowed to cool. This treatment is especially advantageous when the ammonium nitrate is used in the manufacture of explosives.
To Paul Ward and Edward Mammatt Gregory have been granted U.S. Letters Patent No. 454,239, dated June 16, 1891, for the adaptation of a "Composition Suitable for Priming," to the purposes also of detonation, by the addition of a further ingredient to the composition, thus providing a novel, cheap, and effective detonating material, and manufactured at a minimum risk, suitable for use in any fuse or for similar purposes.
They form the chief basis of their explosive composition by the admixture of powdered coke, 2 pounds; amorphous phosphorus, 1 pound; pure chlorate of potash, 75 pounds, with the addition of benzol, chloride of carbon, or acetate of amyl. The amorphous phosphorus and chloride of potash are ground separately in a mortar or other vessel under one of the above fluids. The amorphous phosphorus is then submerged with either of the above fluids. Chlorate of potash is then added and the two ingredients are ground together under sufficient fluid to keep the mass from clogging. When this has been done for a suitable time, coke is added in powder and the whole is again ground for a short time. This forms an excellent priming composition, and by the addition thereto of paraffine or common tallow oil the powder will be enabled to cake together after the grinding fluids have evaporated. This reduces its sensitiveness to friction or percussion without detracting from its explosive violence or its sensitiveness to an electric current, and thus constitutes an excellent detonating composition.
They have found that the detonating effects of this compound are most pronounced when it is detonated by the previous explosion of a priming composition occurring at the closed end of a fuse and detonator-case, where the compression of the gases from the exploding priming composition causes intensely rapid combustion and consequent detonation in the detonating charge.
They state the manufacture, as described, to be much less dangerous than where the usual fulminate of mercury is employed, and that the addition of paraffine oil to the composition serves also to prevent oxidation of the ingredients when stored.
They claim a detonating composition consisting of powdered coke, amorphous phosphorus, chlorate of potash, and paraffine oil, substantially as and for the purpose set forth.
U. S. Letters Patent No. 455,332, July 7, 1891, have been granted Joseph A. Hunt, for a "Blast Cartridge." The invention is described as consisting of two parts of a cylinder, which are hollowed out in their middle so that when they are placed together a recess is formed for the reception of the explosive which may be used. These two parts have each in one end a perforation for the insertion of a fuse, and are made with longitudinal and abutting flanges, which, when the explosive is ignited, permit of the two parts flying apart in opposite directions, thus splitting the log, rock, or other analogous substance asunder. It is said that in using this cartridge no tamping is necessary, that a wet log can be split as easily as a dry one, and that this method of blasting is less dangerous than the old methods, in that the cartridge will not jump out of the log when fired. He claims as new the two halves of a cylinder, recessed as above described, each possessing longitudinal and abutting flanges, with a perforation at the end of each for insertion of a fuse.
Commander F.M. Barber, U.S.N., has been granted U. S. Patent 435,788, Sept. 2, 1890, for a "Method of Floating Stranded Vessels," in which, after pointing out that while one hundred pounds of gunpowder or thirty pounds of gun-cotton will infallibly blow a hole in the side of a ship with which it is in contact, yet at a distance of twenty-five feet horizontally, or ten feet vertically, a vessel using such a torpedo will, while receiving a heavy shock, remain entirely uninjured, he claims: The method of floating a stranded vessel or other object by exploding torpedoes or like agents beneath the surface of the water in the vicinity of the same, thereby causing a shock or concussion and at the same time exerting traction thereon, as by hawsers, from a point outside the vessel, substantially as described.
Under the title "Outbursts of Gas in Metalliferous Mines," B.H. Brough gives, in the School of Mines Quarterly, 12, 13-22; 1890, an account of a number of cases in which gas has been liberated in metalliferous mines, and in some of which serious explosions have occurred. He shows that these outbursts of gas are not always due to the same cause, and he gives the following explanation to account for the formation of the gas in the various cases described: 1. The decomposition, in a mine, of timber in contact with water or moist air may produce fire-damp, which would accumulate in cavities that are ultimately broken into. 2. In iron mines when the iron is not entirely in the state of peroxide, water might be slowly decomposed and hydrogen produced. 3. Fire-damp may be liberated from beds beneath the ore-deposit and find its way through fissures into the workings, the gas being given off from rocks enclosing bitumen in the same way as the natural gas of the United States and other countries. At some of the Derbyshire mines the gas is derived from the Lovedale shales, which are of a bituminous character. 4. Fire-damp may be produced from the decomposition of organic matter in the same way as the hydrocarbon met with in salt mines. 5. In some cases explosions have been caused by outbursts of sulphuretted hydrogen produced by the action of acid waters on pyrites ore. 6. The outbursts of carbon dioxide met with at Foxdale, Freiberg, and Massa Maritima, may have been caused by the action of acid water, produced by the oxidation of pyrites, on lime stones and other metalliferous carbonates.—Jour. Soc. Chem. Ind. 10, 143; 1891.
An explosion, which in many of its features recalls those of Rochester and Pawtucket occurred in Providence, R. I., Sept. 5, 1891, and resulted in fatal injuries to one man, severe to two others, and slight injuries to several others. From the description in the Prov. Journ., Sept. 6, 1891, we learn that private parties have a contract with the city for the disposal of its swill; that as a step in this process the grease is extracted with petroleum-naphtha; that this naphtha is brought once a month in tank cars holding 7000 gallons each; that this naphtha is conveyed from the cars, through a two-inch pipe, 500 feet long, to the works; that on the day of the accident a leak was discovered in the pipe leading from the naphtha tank by which naphtha escaped to the river, and that immediately on discovery the hole was plugged. It was not supposed that any considerable amount of naphtha had escaped, yet, within a few minutes after the hole was stopped, a report was heard from the Woonasquatucket river, and a sheet of flame, followed by a dense cloud of black smoke, was seen to be projected to a considerable height above it. It was found that a pile-driver had been at work in the river, and that the vapor from the naphtha floating by the scow had become ignited at the fire under the boiler.
The N.Y. Herald of Oct. 16, 1891, details the circumstances attending an explosion on board the U.S.S. Atlanta, Oct. 13th, while at sea in a gale of wind, from which it appears that the forward collision compartment being found filled with water through a leak in the hawse-pipe and imperfect closing of the forward hatch, a handy billy was rigged to pump it out, and when after some hours the suction failed, an ordinary lantern was lowered into the compartment to ascertain the cause, whereupon an explosion ensued which resulted in severe injuries through burns to two men, and more or less serious ones to four others, while the collision bulkhead was markedly bulged. A board ordered, of which the writer was a member, found that the collision compartment had been used as a store-room for paint stores in their original packages, and that among them were spar and damar varnishes and Japan dryer, each of which gave off vapors at ordinary temperatures, which formed easily exploded mixtures when diffused through the air, and that this mixing was more readily effected by agitation with salt water under the conditions which prevailed on the Atlanta.
The explosion and fire which occurred June 15, 1891, in compartment No. 73 of the U. S. S. Philadelphia, were traced to a similar source, and the analogy to the Doterel accident and similar ones pointed out. (N.Y. Tribune, Nov. 27, 1891.)
In consequence of this report, the Brooklyn Union of Nov. 11, 1891, states that the Secretary of the Navy has issued an order amending paragraph 34 of page 39 of the Regulations of the Navy to read as follows:
"Spirits of turpentine, alcohol, all varnishes and liquid dryers must be kept in metallic tanks or vessels securely stowed away on the spar deck, and they are never to be taken below except in small quantities for immediate use."
According to the N.Y. World, Oct. 27, 1891, an explosion of a similar nature occurred at No. 69 Pineapple street, Brooklyn, N.Y., Oct. 26, through which a young girl was seriously, and perhaps fatally burned. It has been found that petroleum naphtha or benzoline is a most efficient agent for the destruction of moths, and it is a not infrequent occurrence in establishments where furniture is treated, that, since the fabric is not affected by the naphtha, lounges, mattresses, arm-chairs and the like are completely immersed in the liquid, and retained until saturated.
In this instance the upholsterer employed sought to destroy moths which had gotten into the furniture, and to arrest and repair their ravages, but he endeavored to do this by sprinkling the furniture with naphtha, and closing the doors and windows of the room in the dwelling-house in which the articles were. Some time later the child returning from school opened the door between the room with the naphtha-laden atmosphere, and an adjacent one in which a fire was burning in a stove, when the vapor at once ignited and flashed back.
In the Sci. Am. Sup. 32, 13053; 1891, under the title of the Spontaneous Ignition of Carbon Bisulphide, Dr. Max Popel states that in view of the widespread application of carbon bisulphide in extraction processes, and of the frequent explosions and fires which are caused by its spontaneous ignition—i.e., without its actually coming in contact with flame or any red-hot substance—it is of interest to collect and publish all the observations which have been made concerning the causes of such accidents.
Unfortunately, the nature of carbon bisulphide is by no means thoroughly known; in particular we have no complete data as to its behavior at different temperatures and pressures, mixed with other gases, air, etc., in contact with metals and other substances; and yet a knowledge of these very points is necessary before the substance can be employed with safety. The main difficulty to be met with in the employment of carbon bisulphide is its volatility. Even at a very low pressure (0.1 atmosphere and less) it is quite impossible in an extraction apparatus to prevent its escape by means of taps and the like. Again, the air which is always admitted on filling the apparatus is again drawn out, saturated with the vapor, the loss increasing with the temperature. In the course of some experiments instituted to ascertain the actual amount of material carried away by the air, a spontaneous ignition of carbon bisulphide was observed under the following circumstances: The tube which connected the interior of the apparatus with the air, and which had previously ended near the roof of the building, was bent over and the end allowed to dip about 10 centimeters into a vessel filled with oil. It was found that the oil absorbed the carbon bisulphide almost completely, and that the whole loss, at the temperature of the cooling surface (10°-12°C), was only very small; but that it amounted to several liters in the course of a very few hours at a temperature of 8°-10° above this. A pressure of about one-eighth of an atmosphere was also set up in the apparatus, owing to the descending path which the air had to take, and to the pressure of the oil, and this, of course, affected the boiling of the carbon bisulphide. In order to remedy this, the apparatus was to be removed and replaced by another arrangement. While a workman on the roof was screwing off the descending arm of the pipe. Dr. Popel stood by the oil flask, which was perfectly cold, as was also the pipe dipping with it, and in order to allow a little more room for the motion of the pipe, he placed the flask at a lower level, when just at that moment the workman informed him that the pipe was beginning to get very hot at the joint. He was about to quit the place and see for himself if this were correct, when an explosion took place in the apparatus, and the oil saturated with the carbon bisulphide took fire. In this case, therefore, the spot at which the ignition started could be determined with a certainty which is rare in accidents of the kind. No external influences were possible, and the idea that the explosion was caused by the absorption of oxygen by the oil and consequent heating is disproved by the fact that the whole remained quite cool until the actual moment of ignition. The only probable explanation is that the mixture of carbon bisulphide and air was raised to its igniting point by the heat developed in the pipe by the friction at the bend which was being unscrewed. The pressure being diminished by the lowering of the vessel, the flame spread downward and ignited the oil. The actual temperature attained in this case could not be ascertained, but the following experiment shows that carbon bisulphide and air will ignite even below the boiling point of water. A watch-glass containing carbon bisulphide was placed in a new copper oven with smooth walls; explosion took place regularly at 96°-98°; when the walls were covered with a layer of clay this no longer occurred, so that copper seems to have played an important part in the phenomenon. Mixtures of carbon bisulphide and air readily ignite when brought in contact with iron pipes through which steam at 3 to 4 atmospheres (135°-145°C.) is passing. The less carbon bisulphide there is in the mixture the higher is its ignition point and the sharper the explosion.
It is, therefore, necessary, in places where this substance is employed, to cover all steam pipes, cocks and valves with great care, and also to work without any pressure, so as to avoid loss. Unfortunately it is impossible to employ the vacuum, since the escape of the vapor into the pump cannot be avoided, and explosions would be caused by compressing it when mixed with air.—Chem. Zeit.
T.E. Thorpe describes in J. Chem. Soc. 55, 220-523; 1889, a lecture experiment on the "Decomposition of Carbon Bisulphide by Shock." The apparatus consists of a thick glass tube about 600 mm. long and 15 mm. wide, fitted at one end with a caoutchouc cork, through which pass two stout wires or thin rods. A small brass or iron cup, like a deflagrating spoon, is attached to one wire, and the other wire is bent so as to come within 2 to 3 mm. of the bottom of the cup. About 0.05 gram of mercury fulminate is placed in the cup, the cork is fixed tightly into the tube, which is clamped to a retort-stand and tilted to an angle of 45°; and a piece of paper which is slightly longer than the tube, and which is moistened with carbon disulphide, is placed within the tube, where it remains for a minute or so, when, the tube being practically filled with the vapor of carbon bisulphide, it may be withdrawn. On now passing a spark from a Ruhmkorff coil through the cup, the fulminate will be detonated and will detonate the disulphide, and the internal walls of the tube will become lined with a deposit of soot mixed with mercuric sulphide and free sulphur. Similar effects are obtained by filling the tube with a mixture of carbon disulphide vapor and nitrogen or carbon dioxide, but in these cases the deposit of carbon is comparatively dense, lustrous and coherent. This forms an easy and safe method for demonstrating the resolution of an endothermic compound by shock.
Dr. Thorpe was led to devise this experiment through an observation made while investigating the sulphides of carbon. Low had obtained the C2S3 by the action of sodium amalgam on CS2, and Raab had obtained C5S2 by the action of sodium alone on CS2. Dr. Thorpe used the fluid alloy of sodium and potassium, and treated rectified, dehydrated CS2 with this alloy, when, after a few hours' standing, the alloy was seen to be incrusted with a yellowish-brown powder. On now shaking the bottle to detach the crust, the contents exploded with a loud report, and the operator's hand was coated with a black deposit consisting, apparently, of finely divided carbon. Further experiments showed that the yellowish-brown powder was highly explosive, and that on simply pressing with a glass rod it detonated with even more violence than nitrogen iodide.
He is as yet only able to offer conjectures as to the nature of this powder. It may be a compound of carbon monosulphide and potassium, analogous to that formed by carbon monoxide and potassium. There is some ground for the belief that the highly explosive character of the latter substance is really due to the formation of potassium acetylide, produced by the action of moist air upon it, for it is well known that when thrown into water it detonates with great violence and with the evolution of acetylene. In the case of the compound formed by the action of carbon disulphide there can, however, be no suspicion of the presence of hydrogen.
Attempts were made to effect the decomposition of the CS2 by the use of other explosive agents than the yellowish-brown powder and the fulminates, gunpowder, potassium chlorate and phosphorus, potassium chlorate and ammonium picrate, copper acetylide, nitrogen iodide, Berthollet's silver amine, oxygen and hydrogen, and oxygen and carbon disulphide vapor being used, but they had no apparent effect.
In an article on the "Formation and Decomposition of Carbon Disulphide," Compt. rend. 67, 1251; 1869, Berthelot calls attention to the fact that Favre and Silbermann obtained 258.5 cal. as the heat of combustion of the molugrams of CS2, while the same weight of C and S gave only 24.5 cal., yet at a temperature sufficiently high to decompose the CS2 no explosion took place. In his Sur la Force des Matieres Explosives 1, 196; 1883, he gives the heat of formation of CS2 as —0.55 cal. for the gaseous and —7.2 for the liquid state, and in 2, 149; 1883, he states that he has detonated the endothermic gases by means of mercury fulminate.
Under the rather inept title, "The Direction taken by Explosives," Charles E. Munroe combats, in the Illustrated American 3, 286; 1890, the popular notion that "high explosives explode downwards while gunpowder explodes upwards," and illustrates his argument by photographs of results obtained in practice. One of the most important illustrations unfortunately is presented in the reversed position.
We are indebted to the courtesy of Major J. P. Cundill, R. A., for a copy of the "Addenda to Dictionary of Explosives," bearing date of 1890, which brings the literature of the subject as treated in his very valuable work up to date.
M. Eissler, whose "Modern High Explosives" is so favorably known in this country, has published a "Handbook of Modern Explosives," which is in many particulars a better book, as it covers more ground and contains fresher data. We understand that owing to existing copyright there are some obstacles to the introduction of the work into this country.
Vivian B. Lewes, "Service Chemistry," prepared by the Professor of Chemistry at the Royal Naval College especially for the instruction of naval and military men, gives a very clear exposition of the subject of explosives as regarded from a chemical standpoint.
Through the courtesy of M. P. F. Chalon we are in receipt of his “Note sur les Poudres sans Fumée," which gives an admirable presentation of this subject up to the date of publication.
"Smokeless Powder and its Influence on Gun Construction," by J.A. Longridge, presents the results of the investigation by a well-known ordnance expert of the data available for smokeless powders by the use of Sarrau's formulas. His conclusions are that smokeless powder has ballistic properties far superior to the old powders; that the erosive action on the guns will probably be less; that its use in existing guns of the new forged steel type will not lead to any considerable increase of ballistic effect without considerable risk, owing to the increase of pressure developed in the front part of the chase, although the actual maximum pressure on the gun may be less; that to utilize the high ballistic powers of the new powders very strong guns will be required, and that such guns will have to be much stronger in front of the trunnions than those of the new type forged steel guns: that to arrive at very high ballistic results it is not necessary to have guns of inordinate length, but by the adoption of higher initial, instead of low and more uniform pressures, velocities of 3000 feet per second and upwards are attainable with perfect safety. This points, in his opinion, to the wire system of construction, and he urges that immediate experiments be made to enable new ballistic formulas to be constructed, and determinations made of the tensile strain on the chase caused by the friction of the products of combustion.
B. Westermann announces "Methode zur Zerstorung von Felsen in Flussenmittels aufgelegter Sprengladungen," by Johann Lauer.
Charles E. Munroe has in press Part II. of his "Index to the Literature of Explosives," in which the periodicals indexed in the first part are brought up to 1890; and in addition Dingler's Polytechnisches Journal, Proc. American Chemical Soc, Nicholson Jour., Edinburgh Jour. Sci., and Popular Science Monthly are indexed from date of first issue up to 1890, making in all 843 volumes which have been reviewed.