No. XV.
"The Pneumatic Dynamite Torpedo Gun," which has been attracting so much attention for the past four years, is described and its good qualities set forth at length by E. L. Zalinski in the Jour. Mil. Serv. Inst. 8, 1-35; 1887. The first 2-inch gun was designed and constructed by Mr. Mefford, of Ohio, in 1883; the 4-inch by Geo. F. Reynolds, and the 8-inch by Nat. W; Pratt. To Lieutenant Zalinski belongs the credit of having given direction to the development of this gun so as to render it a practical military appliance, by indicating in a general way the requirements to make it such, and he has labored most zealously to this end. The electrical fuse is alone his personal invention, but it is one of the most valuable and successful features of the system. The projectile used is a modification of a form designed by Colonel John Hamilton.
The 8-inch gun has been worked with 1000 pounds pressure, and at an elevation of 35°, a shell carrying 60 pounds of explosive has attained a range of 2 ¾ miles, while one carrying 100 pounds has attained 3000 yards with 33° elevation. The change in pressure during firing may be corrected by changing the elevation or the "cut off." Thus, in a recent trial, the initial pressure was 1000 pounds and the elevation 14° when, the "cut off" adjustment having been varied, the first round gave a loss of 47 pounds and a resulting range of 1816 yards, while the second round gave a loss of 68 pounds and a resulting range of 2492 yards. Range tables for introducing both variables are to be provided the gunners on a brass plate attached to the pressure gauge.
Lieutenant Zalinski claims for this gun great rapidity of fire. He believes that with trained men the gun may be fired at the rate of once each minute. In the trial before a U. S. Naval Board, in June, 1886, with untrained men and without great effort being made, five rounds were fired in nine minutes and forty seconds. This was with the old form of projectile, involving the placement of the gas check, etc. The accuracy of fire in these five rounds was also remarkable. The range was 1613 yards, the elevation 10° 40', the pressure 1000 pounds, and the "cut off" set to produce a loss of 50 pounds. Four of them attained exactly the same range, the other having gone only seven yards beyond. The maximum lateral dispersion was equivalent to only 6.2 yards. The wind was quite variable, but no attempt was made to follow it except once, just after the first round.
A 2-inch rifle gun has now been built which is to be tested, even to the final bursting of the gun, to establish the limits to which rifling can be safely used. A torpedo cruiser to carry two 10 ½-inch and one 12 ½-inch gun is now building for the U. S. Government. The range of these guns will be at least one mile. The 10 ½-inch shell will carry 200 pounds of explosive gelatine, equivalent, according to Zalinski, to 326 pounds of dry gun-cotton. The 12 ½-inch will carry 400 pounds of explosive gelatine, equivalent to 652 pounds of dry gun-cotton. In comparing the pneumatic gun with gunpowder guns, Lieutenant Zalinski says: "The feasibility of using gunpowder for the propulsion of shell charged with high explosives is continually broached. It has been frequently tried, but invariably with final disastrous results, where the experiments have been carried up to moderately large charges. By large charges, I refer to shell charges not less than fifty pounds and reaching up to one thousand pounds, and even to shell charged with a ton of high explosives.
"The advocates, or rather the predictors, of the use of high explosives from powder guns also demand penetration before explosion. If large charges are to be thrown, the shell must necessarily be made thinner, and it is very doubtful if it will then withstand the concentrated blow it receives upon striking the target, so as to penetrate even a moderate thickness of armor. The battering shell of the 100-ton gun contains a bursting charge of only twenty-five pounds of gunpowder. It would seem that the walls of the shell would have been made as thin as consistent with ability to perforate armor without breaking up.
"Assuming that twenty-five pounds of a high explosive could be substituted for the gunpowder, it is very doubtful if it could be carried through heavy armor successfully before explosion. There is no record of large battering shell fully charged with gunpowder having perforated armor over six inches in thickness, without explosion until perforation. On the contrary, explosion takes place prematurely, almost immediately upon impact, with the result of less injury to the target than that produced by an uncharged shell. Much more surely will this be the case if a high explosive be substituted for the gunpowder, as the bursting charge, unless the shell cavity is well cushioned. To do this involves reduction of explosive capacity. The energy available, after breaking up the very thick and tough walls of steel shell, will be but little greater than produced by the gunpowder. The effect as to the material injury or man-killing power will not much exceed that producible by the shell charged with gunpowder.
"In firing a shell from a powder gun, the walls of the shell must necessarily be sufficiently strong to withstand the initial shock. This limits somewhat the capacity for bursting charge, even when armor piercing is not sought for. If a high explosive is used, some cushioning device is requisite, and a further reduction of capacity ensues.
"Assuming that a shell charged with some of the high explosives can be thrown with safety from a powder gun under normal conditions of pressure, it is known that abnormal pressures, varying there from as much as 5000 to 12,000 pounds per square inch, are not infrequent. This may be looked for especially when the gun is warmed by continuous firing. In addition to this, the shell and the contained charge may become warmed by remaining in the hot gun bore some little time before being fired. The high explosives increase very rapidly in sensitiveness by slight increments of heat. If, then, with this condition of increased sensitiveness we have in addition an abnormal pressure, a premature explosion is very likely to occur. Much more will this be the case when the bursting charge is one of the high explosives. In this connection another matter is to be considered. It is well known that the high explosives are capable of producing more or less violent explosions, depending upon the character of the initial shock or detonation. The more insensitive the explosive the more powerful must be the detonating charge to produce an explosion of the first order. Fulminate of mercury appears to be requisite in all cases. But fulminate of mercury is even more sensitive to shock than either ordinary dynamite or dry gun-cotton; hence the resulting shock must be tempered so as not to explode the more sensitive detonating charge rather than the specially insensitive bursting charge. Wet gun-cotton has been substituted for powder charges, but being quite wet reduces its explosive ability nearly to par with gunpowder. Particularly is this the case where no detonating charge is used of dry gun-cotton and fulminate of mercury. Where the explosion takes place by simple impact, not alone is it of a low order, but, as the initial point of explosion is from the front, the resulting injury to the target is less than from a blank shell." The author quotes Commander Folger, U. S. N., in support of these latter views.
In discussing the effect of tamping the author says: "A cartridge of 8 ounces of dynamite was suspended in superficial contact with an iron plate three-quarters of an inch thick and there exploded. The result was a simple indentation of the plate. A charge of S ounces was again suspended against the plate, but over it was loosely suspended a piece of angle iron open at both ends and of such size that the inscribed circle between its sides and the plate was less than the cross section of the charge, which was cylindrical. Thus there was no direct pressure against the cartridge, yet a large elliptical hole was blown through the plate considerably longer and broader than the cartridge. This experiment was repeated with almost identical results; when both plates were placed together a hole was blown through both plates."
Again: "Comparisons are frequently made as between the high angle fire of the pneumatic gun and the flatter trajectory of high-power powder guns. The comparisons are persistently made, notwithstanding the fact that it should be considered more as a torpedo-projecting machine than as a gun, and that the comparison should be made with torpedoes rather than guns. Nevertheless, even when considered as a gun, its high-angle fire is not altogether a detriment, and possesses important elements of efficiency as such, even when compared with high-power guns.
The experiences at the bombardment of Alexandria, and practice trials from English ships under the most favorable conditions, indicate that the great accuracy of fire of high-power guns is in a measure neutralized by the unstable platform which the ship gives. From this it would appear that naval combats, instead of taking place at ranges of from 5 to ID miles, will rarely begin at much more than one mile range, and the tendency will be to come to closer quarters. Two miles may be considered the longest ranges at which attack of fortifications will take place." Hence, both "will be at such ranges as to make it possible to bring into play the pneumatic gun."
"The high-power guns, with their relatively flat trajectories, will be thrown out as to range, more by slight changes of angle due to the unstable platform, than will the higher angle fire of the pneumatic gun. The change of range due to error of judgment as to proper instant of firing will be much greater with the high-power guns than with the pneumatic gun. The variations of the latter are more likely to come within the limits of error in judgment of distances.
Again, at the short range mentioned, the high-power guns have, owing to the flatness of their trajectory, only the vertical projection of the sides and turrets of the ship as the available target, and missing these, no result can follow. This portion of the target is most heavily armored. On the other hand, the torpedoes from the pneumatic gun have, primarily, the over-water hull of the vessel, involving both its deck, which is relatively large in area and weak in armoring, and the vertical target to which the high-power guns are limited. To this last, if the caliber of the gun is moderately large, serious injury may be done, directly and indirectly while the deck, if struck, is sure to be crushed in.
But, in addition to the over-water hull, it has the very great chance of doing fatal injury to the under-water hull, if missing the direct hit of the target.
No small element, in considering the effectiveness of this weapon, will doubtless be the moral effect. The knowledge that escape is not assured when the enemy's missile has failed to make a direct hit, and that the danger may even be enhanced by that miss, will not have a reassuring effect on the crew of the vessel attacked."
The writer then considers the use of this weapon for coast defense, countermining, for defense of ships, and as an adjunct for ships in ramming, and for torpedo rams. The paper is illustrated with a number of cuts.
By direction of the Secretary of the Navy, a test of the pneumatic gun was made September 20, 1887, by anchoring the Silliman (a condemned coast-survey schooner, 80 feet long by 20 feet beam) at a distance of 1980 yards from Fort Lafayette, and using her as a target. The projectiles contained 55 pounds of explosive gelatine each, and three of them were sufficient to completely wreck the vessel. A description of the trial may be found in the Army and Navy Journal or the Register for September 24, 1887. Instantaneous photographs of the appearance of the target after each shot occur in the Scientific American, October, 1887. Some delay having arisen during the experiments with the Silliman, additional experiments for rapidity in firing were, according to the Army and Navy Journal, October 8, 1887, made September 30. Ten shots were fired, each projectile being loaded with 55 pounds of sand, and weighing complete 140 pounds. Firing commenced at 10.42 A. M. and ended at 10.52.30, or about one shot a minute. In the next shot the projectile contained 100 pounds of sand, and it weighed filled 203 pounds. With an elevation of 32°42' it had a range of over two miles and a half. Time of flight 24 ½ seconds. Initial pressure of compressed air 975 pounds, final 825 pounds. Two similar projectiles, with an elevation of 15°, were fired with the gun sighted for 15 yards to left of target. The shots fell within 3 yards to left. The first projectile was 10 seconds in flight; initial pressure 750 pounds, final 625 pounds. The second was 9.04 seconds; initial pressure 750 pounds, final 615 pounds. Range 1772 yards. Of the time shell fired, two fell short 50 to 70 yards. Six would have hit a target the size of the Silliman, and two would have exploded sufficiently near to have injured her seriously. This was the first time that rapid firing with a large number of shell had been attempted, and the result indicated that a modification in the connections between the storage reservoirs and the gun was needed.
The experiments with this gun have given rise to considerable discussion. General Berdan gives his opinion of the value of the trial in the Army and Navy Register, October 8, 1887, to which Zalinski replies in the New York Commercial Advertiser, October 17, summarized in the Army and Navy Register, October 22. In the New York Commercial Advertiser, August 30, Zalinski also replies to the criticisms of General H. L. Abbot. In an interview in the Washington Post, October 16, Lieutenant John P. Finley, of the Signal Service, criticises the gun in the light of the dynamite experiments made at Sandy Hook, and points out how moisture on the hands or in the atmosphere may prematurely fire the electric fuse. The merits of the gun are strongly defended by Colonel John Hamilton, in the Army and Naval Journal, October 29. This is but a minute part of the Literature to which this invention has given rise.
Lieutenant C. A. L. Totten, U. S. A., proposes, in the Army and Navy Journal, July 23, 1887, that "Dynamite Archery" be resorted to, ships being armed with catapults, and dynamite gre7iadiers with crossbows from which arrows tipped with dynamite may be thrown.
Experiments in firing shells loaded with dynamite, by Mr. B. D. Stevens' method, were tried October 11, 1887, at the State Arsenal, Montpelier, Vt. The piece was a twelve-pound brass Napoleon; the shells were spherical, and the charge one-half pound of 35 per cent dynamite, a time fuse being used. The shells were fired with the usual service charge of two and a half pounds of powder. Five rounds were fired without any premature explosion. (Army and Navy Register, October 15; Army and Navy Journal, October 22, 1887.)
From the Daily News, Newport, R. I., October 24, 26 and 28, 1887, we learn that experiments have been made at the torpedo station to test the process proposed by Mr. Serge D. Smolianinoff for firing nitroglycerine with safety from gunpowder guns. His secret consists in rendering nitroglycerine perfectly insensitive to concussion or to detonation by heat, or by any means except by his patented burster. He further claims to be able to explode his shell at any point of the trajectory or after penetration.
The experiments consisted, after some preliminary trials, in firing shells filled with the mixture from service guns with two-pound charges of powder. Three filled shells, unfused, were fired at a stone
wall forty-seven paces distant, without premature explosion. The remainder, fused, were fired up the bay. There was no premature explosion in the bore, and the shells exploded in mid air at a distance of about a mile, after about five seconds.
Mr. Smolianinoff had previously fired over 300 shells from a condemned 20-pound rifled Parrott, using an 8-inch conical shell completely filled with the prepared nitroglycerine, and a 3-pound charge of Dupont's F. F. powder, without having had a failure. The account of some of these earlier experiments will be found in the Daily Alta, San Francisco, Cal., June 13, 1887.
The Illustrated Naval and Military Magazine5, 402-412, December, 1886, contains a quite interesting paper on the use of "High Explosives in Warfare "; meaning thereby their use as charges for projectiles from guns. The paper opens with a lengthy description of the pneumatic gun. This is followed by an account of the experiments made by the U. S. War Department with explosive gelatine, and finally the experiments in Germany, Italy, Switzerland, and elsewhere with gun-cotton, hellhofite, romite, Parone's explosive, and nitrocolle. The paper is liberally illustrated with cuts of apparatus and projectiles, and of fortifications and the like, showing the effect of the explosions.
It is staled that romite is a solid, containing neither nitroglycerine, gun-cotton, nor any analogous compound. It can only be exploded in a closed vessel by means of a dynamite cap, but this may occur at the lowest temperature. It can be manufactured without an extensive plant and at an extremely cheap rate. Romite was invented by Mr. Sjoberg, a Swedish engineer, and has been tested in shells by the Swedish artillery. The results were considered satisfactory, but only small amounts were used.
Parone's explosive consists of two parts of potassium chlorate and one of carbon disulphide. From experiments in Italy with the g-cm. and 15-cm. projectiles it was concluded that this mixture was an exceedingly safe one; that it would not explode without a fuse—not always a desirable quality—and that although its effects were not strikingly superior to those of powder, they increased rapidly with an increase of caliber. On the strength of this report the explosive was fired from a 24-cm. mortar at a range of 3000 m. The mortar burst at the first discharge. The commission recommended the separation of the two constituents of the mixture, but this plan does not seem to have worked well.
Nitrocolle is, according to the Belgique Militaire, a new explosive discovered in Belgium, which is as powerful as nitroglycerine, but much easier and cheaper to manufacture. To make it, strong glue is placed in cold water until it has absorbed the maximum quantity of the latter; the mixture is next solidified by means of nitric acid, and afterwards treated with a mixture of nitric and sulphuric acids, as in the preparation of nitroglycerine. The resulting substance is finally washed several times to remove the excess of acid.
In summing up the results of the Italian experiments executed with the Gruson shell, the Rivista d' Ardglicria e Genio considers that the Hellhoff 's composition is a perfectly safe explosive, but that its power is by no means so great as had been expected.
In conclusion the writer says, although these experiments furnish few instances of full and complete success, we may infer that the future of high explosives is assured. It can now only be a question of time before the use of these agents in powder guns is rendered safe and effective.
An interesting series of experiments on Roburite was carried out on June 14 at the School of Military Engineering, Chatham, under the superintendence of Major Sale, R. E. This explosive belongs to the Sprengel class, being a mixture of two substances, neither of which separately possesses explosive properties; in this case both components are solid, and the resulting mixture has a sandy, granular appearance, somewhat resembling the commonest yellow sugar. Roburite is the invention of Dr. Carl Roth, a German chemist, who claims for it the following advantages over other explosives:
1. That the two components are perfectly harmless and inert separately, so that they can be stored and transported without any restriction whatever.
2. That even when mixed or ground up together in ordinary coffee, cement, or flour mill, the mixture is perfectly safe to handle and use, as neither percussion, friction, nor the application of an ignited or heated body will cause it to explode; this can only be affected by using a detonator charged with fulminate of mercury.
3. That, when detonated, roburite produces neither spark nor flame, and will not -therefore ignite either fire-damp or coal dust in mines. Dr. Roth states that this point was decided by the trials of the Imperial German Commission upon Accidents in Mines, and that in consequence this explosive is now being introduced into the coal mining regions of Germany, as affording absolute safety to the men employed.
4. The amount of noxious gases produced by its explosion is so infinitesimal that for this reason alone it is superior to other explosives in common use for deep mining work. The report from a mine in Westphalia, with shafts about 1500 feet deep, states with reference to roburite : "The men are not inconvenienced by the gases, and experience no difficulty whatever in breathing the moment after a shot has been fired, and they resume their labors at once."
5. Roburite is not subject to deterioration through climatic variations of temperature. It should be kept dry, but if it becomes damp, its strength can be safely restored by drying.
The object of the trials was to test roburite in comparison with gun-cotton, dynamite and blasting gelatin. The program of the experiments actually carried out was as follows:
A. Safety Tests.—After being ground through a small hand mill, the substance was struck direct and glancing blows with heavy hammers upon iron plates, without any result. Flame was then applied to a portion of it by means of a short length of Bickford fuse, but without igniting the mass; thrusting a red hot iron from a portable forge into the roburite caused only slow combustion and crepitation locally, which ceased when the iron was withdrawn. When a quantity was put on the forge fire it merely burned away like an ordinary combustible. Dr. Roth wished to fire a powder charge in contact with the roburite, but it was considered that the above named tests were more severe.
B. Tests on mild steel plates 2 ft. 6 in. by 2 ft. 6 in. and of various thicknesses. These plates were laid flat in shallow trenches, a hollow being left underneath the central portion of each plate; heavy timber balks were stacked around each square trench, with the object of showing the comparative dispersive force of each explosive.
1. Three pounds each of dynamite and roburite were placed on the centre of plates 2 in. thick, some sandy loam being piled loosely on top. The results of detonation were that the dynamite produced a dent in centre of plate 1 ¾-in. deep; the indentation produced by the roburite was about1 ½-in. deep, but the bulge appeared to have a wider area than in the former case.
2. Five pounds each of roburite and gun-cotton were then exploded upon the same plates, with the result that, in the former case, the plate was smashed into four tolerably equal pieces, while the guncotton made a breach through the centre of the plate somewhat resembling that which would be caused by the penetration of a large projectile. The diameter of the hole was roughly 12 in., with five radial fissures almost reaching the edges, the longest 15 in., the plate being at the same time bent into the shape of a pack saddle; this would seem to have been a remarkably tough piece of metal. The timber balks were scattered in all directions.
3. Eight pounds each of dynamite and roburite were then detonated upon plates 3 in. thick. The dynamite caused an indentation 2 ½-in. in maximum depth, while the roburite gave a bulge 3 in. deep in the centre, and of a larger area, reaching apparently almost to the corners of the plate.
4. This series of tests was concluded by exploding 12 pounds each of roburite and gun-cotton on plates 4 in. thick, rather more loam being heaped on top of each. The roburite caused a wide indentation it in. deep in centre, while the tremendous local force of the gun-cotton was exemplified in a striking manner. In addition to an indentation 3J in. in greatest depth, a small crack appeared to extend right through the plate, this crack corresponding with one edge of the lowest slab of gun-cotton, the rectangular shape of which could be clearly seen indented on the steel plate, the depth being ¾ in. at the crack and ½ in. along the other edges of the slab. There is a circular hole drilled in the slab of wet gun-cotton to receive a small cylindrical disk of dry gun-cotton as a primer, and the position of this disk was marked by a circular hollow in the steel plate in. deep in centre.
C. Blasting or Mining Test in Brickwork.—Three holes, each 1 ½-in. in diameter and 18 in. in horizontal depth, were drilled in the solid brick-work of the counterscarp wall, and were respectively charged with 2 oz. of gun-cotton, blasting gelatin, and roburite; the holes were then tempered with loam in the ordinary manner, and fired by means of short lengths of Bickford fuse. The gun-cotton produced no apparent effect upon the brick-work, but Major Sale was of the opinion that the hole must have been open, or very weak, at the back. The blasting gelatin produced violent local action, displacing the brick through which the hole had been bored and the four adjacent to it. There was a slight bulge in the wall, the cracks extending radially from 10 in. to 12 in. The roburite exhibited a more widespread rending action upon the wall, the radius of disturbance being 15 in. or more, and the bulge being also greater. Rather larger charges of each explosive would have afforded a more satisfactory comparison.
D. Ground Mines.—Ten pounds each of gun-cotton, blasting gelatin, and roburite were loaded into holes in the bottom of the ditch 4 ft. deep by 8 in. in diameter, filled up with sand and slightly tamped. The explosion of these charges cast up tremendous fountains of loam and sand, and resulted in the following craters: Gun-cotton, 10 ft. 6 in. wide by 1i ft. 8 ½-in. deep; gelatin, 14 ft. 6 in. wide by 3 ft. 7 in. deep; roburite, 12 ft. 3 in. wide by 2 ft. 9 in. deep. The explosion of the gun-cotton mine appeared to cause great local action; but it will be seen that the area and depth of its crater were considerably less than that caused by the roburite, which again must yield the palm in this instance to the blasting gelatin. It is, however, to be remarked that these mines had been placed much too close to one another, so that their craters crossed; this would give whatever charge was the last to explode a certain advantage.
In summing up the results of the foregoing experiments we must bear in mind the great difficulty—we had almost said the impossibility—of obtaining any absolute standard of comparison of the relative strengths of two or more explosives. Each will seem to prove itself superior for certain purposes. Judged, however, by any standard of comparison, it appears that the new explosive has acquitted itself very well, and, especially when we consider its absolute safety, must have a great future' before it. Roburite has shown itself to be in some respects more powerful than dynamite, to which it is likely to prove a serious rival in the industrial field, although the latter has the proverbial advantage of strong possession of the ground. An important element in the struggle for ascendency will be the price at which roburite can be supplied as compared with dynamite, and this will be, we understand, strongly in favor of the new substance.
As regards the military application of explosives, there is nothing in the results of these trials to disturb the firm conviction of our Government that gun-cotton is the best adapted for torpedo charges, submarine mining, and hasty demolitions of all kinds. Its superiority in local force to dynamite, when employed without any confinement, is once more strikingly demonstrated, to say nothing of the far greater safety of wet cotton and its applicability for use under water with no other confinement than that of a net to keep the slabs together. But although quite outside the scope of Tuesday's experiments, the great power and perfect safety of roburite seem eminently to fit it for use as a bursting charge for shells, into which its granular form would allow it to be conveniently loaded. Much stronger than any picric powder, and doubtless better able to withstand the concussion of the discharge of the gun, an extended series of trials would be necessary to determine the best mode of so employing it. (Engineering, 43, 573. 574. June 17, 1887.)
The Army and Navy Journal, October 1, 1887, quoting from the London Times, gives the name of the reported new Russian explosive as Sleetover, and states that it is equal in strength to pyroxyhne, and very cheap. "Another great superiority which it possesses over all the known explosives of the dynamite class is that when fired its force does not strike downward, but entirely in a forward direction, so that it can be used for all the purposes of cannon and musket charges to which ordinary gunpowder is now applied, without any damage whatever to the weapon from which it is discharged. It is stated, in fact, that ball cartridges loaded with it have been fired out of card-board barrels, as a test, without the least injury to the latter."
The "new Swedish explosive," bellite, discovered by Mr. Carl Lamm, director of the Rotebro Explosive Manufactory, Limited, near Stockholm, consists of ammonium nitrate and dinitro benzene, which, when in a melted condition (the melting point is 80° to 90° C), are mixed with saltpeter, forming a compound of which each molecule explodes. Bellite, when pressed warm, has a specific gravity of 1.2 to 1.4 in its granulated state, which, according to the experiments already made, seems to be the one best suited for military purposes. One litre, of bellite weighs 800 to 875 grams.
Heated in an open vessel bellite loses its consistency at 90° C, but does not begin to separate before a temperature of 200° C. is reached ; at that point evaporation begins, and increases with a higher temperature, without, however, explosion occurring. If the heating is sudden, bellite will burn with a sooty flame, something like tar; but if the source of the heat is removed, the bellite will cease burning and assume a caramel-like structure, the ingredients being the same as in its original state, with the exception of a somewhat reduced proportion of saltpeter. The explosive appears to absorb little moisture from the air after it has been pressed; if this operation is performed in the hot state, the subsequent increase of weight is only 2 per cent.
From the experiments of Werner Cronquist and Professor Cleve we learn that when bellite is subjected to the most powerful blow a man is capable of inflicting with a steel hammer upon an iron plate, it becomes heated, but neither explodes nor ignites. Two grains of bellite in a blank copper cartridge (that of a Remington rifle) were placed on an iron plate and subjected to the fall of a weight of 200 pounds from a height of 17 feet 6 inches, without exploding. Layers of bellite .47 inch in thickness on wood or iron have been pierced with rifle balls fired at a distance of some 50 yards, without showing signs of exploding or ignition. While boring in cast iron with a steel drill, one grain of bellite has been placed in the hole, neither explosion nor ignition having resulted, although no sort of oil or other lubricator was used. A small quantity was fixed to the pointed end of a steel rod, and the rod knocked so hard against quartz as to produce sparks, yet there was no explosion. A good sized piece of bellite was placed in an open tin box and covered with gunpowder, the latter was ignited, the explosion throwing the bellite several yards in the air, but it did not explode. In a piece of hard wood a hole was made of the size of a penholder, two grains of bellite were pressed hard into the hole and this closed with a wooden cork. The wood was thrown into a coke fire and consumed, but there was no explosion. A compressed bellite cartridge was placed close to a rocky wall, and some three inches from it a cartridge of nitrolite (nitroglycerine, gun-cotton and nitrate of ammonia) ; the latter charge was made to explode by a Stubine percussion cap, and after the explosion the bellite cartridge was found to have been crushed, and the powder into which it was turned was fixed to the rock. The bellite had consequently not exploded. The list of these experiments might be considerably increased, but sufficient has been said to prove that bellite can withstand blows, fire, friction, and vibration, without the slightest risk of explosion. It can be safely transported by rail, and stored without any danger of spontaneous combustion.
Granulated bellite is caused to fully explode by the aid of a small quantity of fulminating mercury, even if its cover only consists of thin tin. When pressed warm, especially when it is in the form of hard cakes, it requires a stronger impulse and a stronger cover, which must adhere to the bellite.
The suitability of bellite as an explosive for grenades (when these are provided with a proper percussion tube) has been established through a series of experiments carried out by officers of the Swedish Royal Artillery. A series of experiments has been made by exploding under water, mines loaded with bellite against a dynamometer. The average of several explosions gives, at a distance of 17 ft. 6 in., a blow of equal power to that caused by a weight of 22 pounds falling from a height of 39 in. At a reduced distance of 12 ft. 6 in. the effect was proportionately increased. On comparing the efficiency of bellite with that of gun-cotton, under exactly similar circumstances, the former shows a superiority of 10.4 per cent at a distance of 17 ft. 6 in., and of 15.2 per cent at a distance of 12 ft. 6 in. The firing of 25-millimetre machine-gun ammunition and steel bullets against mines loaded with bellite had not the least effect upon the explosive, thus proving it to possess a great advantage in this respect over other explosives generally used for submarine mines.
It is the opinion of those who have had the best opportunities of judging, and whose verdict is of acknowledged authority, that bellite bids fair to become of great importance; that it is equally suitable for mining and military purposes, while it is not so liable to be put to an undesirable use as are most other powerful explosives. (Engineering, 44, 18, July 1, 1887.)
The press reports that an accidental explosion of melinite occurred at the arsenal at Belfort, March 10, 1887, by which six men were killed and eleven wounded. The Army and Navy Journal, May 14, states that in spite of this accident, and of a more recent one at Bourges, the belief in the new explosive is not abandoned, and that shells filled with it are to be tried against the Belligueuse, one of the early ironclads, of 3617 tons displacement. The Germans, however, claim to have proved by experiment that melinite decomposes if kept long, and is therefore useless for war purposes.
U. S. Letters Patent No. 350048, September 28, 1886, have been granted to Eugene Dupont for a gunpowder press, in which two hydraulic rams, furnished with pins, work through each face of the mold plate. The result of this operation is that the powder in the apertures of the mold plate is compressed with equal force at both ends, and large grains of the desired dimensions and form (cylindrical or prismatic) are produced, in which the ends of the grains, being compressed with equally-moving pistons or rams, are both hard, while the central parts of the grains are comparatively soft when the grains are removed from the molding apertures. A grain of such construction, having two hard ends and a comparatively soft centre, is of great advantage in firing large ordnance, as it burns with great rapidity from the centre as well as the ends when once started, though the initial rate of combustion is slow, owing to the compacted ends. What he claims is—
In a machine for forming grains of explosive compounds, the combination of a fixed mold plate containing suitably formed apertures for molding powder; two equally-moving and balanced rams acting to compress the grains from both ends, and pins passing through the apertures in said mold plate and having a longitudinal motion therein independently of said rams, substantially as and for the purposes described.
U. S. Letters Patent No. 35261 1, November 16, 1886, have been granted Eugene Dupont for an explosive compound, in accordance with the following specification:
My invention consists in the use, in explosive compounds, of wood slightly changed in its chemical formula by the application of heat for the two purposes of increasing the ballistic force of the powder and of controlling the rate of combustion so as to adapt it for use in heavy charges behind projectiles of great weight, or to lighter charges in medium sized guns. With this end in view, I replace (either wholly or partially, as desired), the charcoal which is used in the composition of ordinary gunpowder, with the requisite amount of wood slightly changed in its chemical formula by having been subjected to heat or baked, as hereinafter described.
I have found that branch-willow wood is well adapted to the purpose; but any suitable wood for making gunpowder charcoal may be used.
I subject the wood to a gentle heat (either in a retort over a slow fire, or by the application of superheated steam in a suitable vessel), gradually raising the temperature to about 450° Fahrenheit, at which the heat is maintained for about two hours (this would be for three fourths of a cord of willow), the entire time consumed in the baking being about eight hours, six hours being consumed in obtaining the proper temperature. The limits of temperature at which the baking should cease (as far as I am now aware) to secure good results are 300° Fahrenheit and 450° Fahrenheit, the lower temperature making the wood less rapidly combustible, and the higher securing a more combustible wood. The process of heating the wood, as described, should cease before the wood is transformed into red charcoal, which is useless for my purpose, as red charcoal has entirely lost the fibrous character of the wood, while in the wood which I use in the present invention the fibre is still undestroyed; and it is by breaking the wood and examining if the fibre has been destroyed that I am able to determine the point at which the baking should cease. 450° Fahrenheit is a temperature high enough to transform the wood into red charcoal, if maintained for a length of time; but I remove the wood before such transformation takes place.
My baked wood differs from red charcoal not only in its physical character by retaining its fibre, but also in its chemical formula. Red charcoal is considered to contain about 72.64 per cent of carbon, 4.71 per cent of hydrogen, 20.08 per cent of oxygen, and 0.57 per cent of ash. Although not a definite chemical compound, but being produced by partial decomposition, it will vary slightly in its formula. This also applies to my baked wood, which may vary even more than from 47.51 per cent of carbon, 6.12 per cent of hydrogen, 4.29 per cent of oxygen, and 0.08 per cent of ash, to 51.82 per cent of carbon, 3.99 per cent of hydrogen, 43.94 per cent of oxygen, and 0.22 per cent of ash; but, as will be seen, it has much less carbon than red charcoal, and still less than black charcoal. The carbon in my baked wood also retains to a certain extent, after being ground fine, its cellular form, and combines with the liberated oxygen from the saltpeter more readily than other forms of carbon, for instance, stone coal or lamp black.
The greater proportion of the oxygen and hydrogen in my baked wood than in charcoal is of very great importance to the ballistic effect of the powder. The theory of their action, as proved by experiment, is as follows: The temperature, after ignition of the charge in the gun, reaches 4000° Fahrenheit, a degree of heat too high to permit the oxygen and hydrogen to combine to form water, and they therefore must remain uncombined until, by the expansion due to the motion of the projectile toward the muzzle, these gases are cooled sufficiently to permit their union. When this takes place, a very large amount of heat is disengaged, which expands again the steam and other gases formed by the combustion of the powder. The pressure thus sustained while the projectile is in the gun insures a high velocity and a low pressure, because all the atoms of the powder cannot form new combinations at the time of ignition, but part of them unite as the pressure falls. It is therefore important to get as much of the substances containing oxygen and hydrogen in proportions to form water, or approximate proportions, into the powder as possible, and I therefore prefer the baked wood, which contains these gases in such proportions, besides having its carbon, as stated, in a form to unite readily with oxygen. The fibrous character of my baked wood also gives toughness to the grains of powder and prevents the grain from breaking up too rapidly.
It is unnecessary to describe the method of combining the components of powder, for that is well known, but I have found the following ingredients and proportions to form a desirable powder for guns of twelve-inch caliber: saltpeter, seventy-eight parts, by weight ; sulphur, three parts; baked wood, 12.5 parts; ordinary wood pulp, 2.5 parts; sugar (the use of which forms the subject of my application for letters patent, filed August 12, 1885, No. 174214), four parts; or, as I have also found the wood pulp may be omitted, as the grain will be toughened by the fibre of the baked wood, the proportions in this case being about as follows: saltpeter, 78.95 parts, by weight; sulphur, three parts; baked wood, 15.02 parts; sugar, 3.03 parts.
I do not limit myself to the special ingredients or proportions given above, as my invention consists in the combination of baked wood, as herein described, with well known gunpowder ingredients, and
other equivalent ingredients may be substituted for those above mentioned.
What I claim is—
An explosive compound consisting of a nitrate and sulphur combined with charcoal retaining its fibrous structure, substantially as described.
In U. S. Letters Patent No. 363887, dated May 31, 1887, Eugene Dupont claims to have invented a new and useful compound, principally for use in guns of medium and large caliber, of which the following is a specification:
The first object of my invention is to obtain an explosive which shall have great ballistic force; and its second object is to obtain a powder which shall obviate, as far as possible, the many disadvantages pertaining in a greater or less degree to all artillery explosives, and which consists in the smoke arising from the burning powder, such smoke obscuring the view and interfering with the sighting for a second shot.
I have found by experiment that substances having in their component parts the elements of hydrogen and oxygen in such proportions that, upon being released from the rest of the component parts by combustion, they will combine to form water and steam, and greatly increase the explosive force of the powder of which they form a constituent element. The action of such powders seems to be as follows: Upon firing the charge, the gases confined in the powder are released, and act to expel by their expansion the projectile toward the muzzle of the gun. This I term the "first explosion." At this time the oxygen and hydrogen are released as gases, but under too great heat to unite in the form of steam. As the pressure is decreased by the motion of the projectile in the gun, this heat also decreases, and the gases—oxygen and hydrogen—unite in the form of water. The heat generated by this union at once changes the water into steam, and this expansion, which takes place before the projectile leaves the muzzle of the gun, I term the "second explosion." There is thus formed a powder of great explosive force, which acts twice upon the projectile. I have also found that such powders are very effective in dissipating the smoke arising from the discharge, owing, as I suppose, to the fact that the steam, generated as above stated, condenses, and in so doing absorbs large quantities of the carbonate of potash, the solid portion of the result of decomposition of a charge of powder and that portion which forms the smoke.
Thus I employ in place of the carbon usually used in the composition of explosive powders, the substances known as "carbohydrates," and which have the chemical formula of cellulose, or an approach to it, such as wood pulp, starch, dextrine, etc., or other substances, such as sugar, having substantially the chemical formula of C12H22O11. All such substances having substantially the formulas aforesaid, and the capacity of forming water and steam by the action of the explosion, I term in this specification "carbohydrates." Instead of using one substance having the required chemical formula, two or more may be used having the necessary elements separate, which, when liberated, will combine to form steam and act in the manner required.
The materials should be mixed in a finely divided condition, and it is better to mix the carbohydrates with the other ingredients of the powder after such other ingredients have been mixed, as such carbohydrates are apt to be gummy in their nature.
I have found, for example, that a very effective powder may be made of the following substances, in substantially the proportions specified, viz., saltpeter (for which other known nitrates may be substituted) 78 parts, sulphur 2.8 to 3 parts, carbohydrates 3 to 4 parts, charcoal retaining its fibrous structure 12 or 12.5 parts. This powder, to be most effective, should be made in prismatic grains, and I have found that the best results are obtained by so constructing said grains that they are less dense in the middle than at the ends, which therefore have the particles more compacted together at those points than in the middle. My method of making these grains of such varying density is described in an application for letters patent, filed August 12, 1885, Serial No. 167749. Such form and construction of the grains retard the development of the gases from combustion, until it is desired to obtain the maximum force; and I find that the fibres of the charcoal, retaining its fibrous structure referred to, materially aid in this result, as they tend to prevent the grains of powder from becoming broken up. The use of charcoal retaining its fibrous structure, as above referred to, forms the subject of an application for letters patent, filed June 5, 1885, Serial No. 167748.
What I claim is: 1. An explosive compound consisting of a nitrate, sulphur, charcoal retaining its fibrous structure, and a carbohydrate, substantially as described.
2. An explosive compound consisting of saltpeter, sulphur, charcoal retaining its fibrous structure, and sugar, substantially in the proportions specified.
From Ding. Poly. Journal, 263, 149; 1887, we learn that the composition of the brown prismatic powder sometimes known as cocoa powder is yet a secret, but it has been suggested that the charcoal used in its manufacture is made from peat, and the mysterious actions of the inventor tend to confirm this opinion. It is stated also that charcoal for this purpose is made at Chilworth and elsewhere by the action of superheated steam on rye straw.
We have frequently been asked to state to what the properties which distinguish the brown prismatic powder are due, and we trust it may not be considered out of place if we state our theory in this connection.
We hold that its property of imparting a high initial velocity to the projectile, while only exerting a relatively low pressure on the walls of the gun, is due to the combined action of a number of causes, viz:
I. The form of the grain; 2. the size of the grain; 3. the great density of the grain ; 4. the great hardness of the grain ; 5. the small percentage of sulphur; 6. the easy inflammability of the charcoal or carbohydrates ; 7. the relatively great heat evolved ; 8. the simplicity of the chemical reaction.
Cause 5 tends to reduce the readiness with which the powder will ignite, or raises its point of ignition, even when the grain is pulverized. Causes 1, 2, 3, 4, and 5 combined operate, so long as the first four exist, to produce a very slow rate of combustion. By the time, however, that the projectile is moved from its seat, the grains will be reduced in size and more or less broken up. We shall then have a fine-grained powder which is highly inflammable at the temperature which exists (cause 6), and consequently the volume of gas evolved will increase rapidly as the volume of the chamber increases. Owing to the relatively great quantity of heat evolved (cause 7), the cooling effect of the envelope is less marked than with other powders. As the chemical reaction is a comparatively simple one (cause 8), the speed of the reaction is probably more uniform than when the reaction is more complex, as in other powders.
According to Berthelot, dissociation plays an important part. This is possible, and even probable, with powders made from under burnt charcoal, as this contains carbohydrates, or with those in which the carbohydrates are a constituent of the mixture.
The advantage of the form of grain employed was pointed out by Rodman, the inventor, and his views have been confirmed by Sarrau. The advantages of size, density (this is 1.86 in cocoa), and hardness are commonly known. Berthelot and Vieille J have shown that the hydrates of carbon, such as cellulose, contain an excess of energy above that given by the carbon and water which their decomposition would furnish. And Noble states, in his lecture on the "Heat-Action of Explosives," that a unit mass of cocoa powder yielded a greater number of units of heat than any other of the standard powders, which Abel and Noble tested, yielded. He also shows H that the chemical reaction attending the combustion of cocoa powder is simpler than that attending any other.
U. S. Letters Patent No. 362899, May 10, 1887, have been granted to Thorsten Nordenfelt, of Westminster, England, and Victor A. Meurling, of Christianstad, Sweden, in accordance with the following specification:
At the present time, in the manufacture of gunpowder, it is usual to incorporate the sulphur and saltpeter with the other materials by a process of grinding. This grinding is a dangerous operation after the saltpeter is added, and it has to be long continued in order that the mixture of the materials may be sufficiently intimate. Now, in place of thus producing a mechanical intermixture, which, after all, can only result in placing minute particles of sulphur, saltpeter and charcoal side by side, we bring the sulphur to a state of solution in bisulphide of carbon, and in this state we combine it with suitable carbonaceous matter. In this manner we diminish risk in manufacture, we manufacture the powder more cheaply, and obtain a powder which is more even in its results.
If it be deemed desirable to use wood charcoal, it may be employed as the carbonaceous matter in the manufacture of the gunpowder in carrying out our invention; but as we have found cotton or wood fibre or other like vegetable fibre reduced to a state of fine powder by a chemical process a preferable carbonaceous matter, we employ it. The vegetable fibre, whether it be cotton or wood fibre such as is used in paper making, or other vegetable fibre, is placed in a loose state in a vessel through which a current of hydrochloric gas is caused to pass so that it may permeate the fibre. After a time the fibre will be found in a friable state, such that it may easily be reduced to powder by friction. The current of hydrochloric gas is then stopped, and is replaced by a current of air, which is continued until the gas is thoroughly expelled.
The following is the manner in which we conduct the manufacture of gunpowder: The ingredients are sulphur, saltpeter, and the carbonaceous matter. The materials should be pure, and the proportions the same as now used in gunpowder, subject to variation to some extent, and, as is now usual, to adapt the powder to the various purposes for which it is required.
We first grind the carbonaceous matter to a very fine powder, the finer the better. We prepare the sulphur for use by dissolving it in bisulphide of carbon. The solution is affected by the aid of a gentle heat in a water-bath, and the evaporation of the bisulphide may be prevented by covering its surface with a layer of water. A saturated or nearly saturated solution should be thus prepared. The pulverized carbonaceous matter and the solution of sulphur in bisulphide of carbon are then thoroughly mixed together in a closed vessel containing a mechanical stirrer. When the mixture is complete, the solvent is evaporated or distilled off by the aid of a gentle heat. The vapor of the bisulphide is collected and condensed, so that the solvent may not be lost. The means for this purpose may be such as are employed when this liquid is used in the preparation of extracts and for like purposes. When the bisulphide of carbon is evaporated, the carbonaceous matter and sulphur remain intimately mixed, and each particle of carbonaceous matter has become impregnated with sulphur, instead of as at present, where the admixture is obtained by grinding, the particles of carbonaceous matter and sulphur being only mechanically placed side by side. The saltpeter is prepared for use by dissolving it in water, the solution is added to the pulverized carbonaceous matter already impregnated with sulphur as described above, and the whole is stirred together in a mechanical mixer.
We find it advisable not to add the whole of the saltpeter at one time, but to divide it into two or three separate quantities, and with each quantity we have sufficient water to render it sufficiently fluid for impregnating the carbonaceous matter already impregnated with sulphur.
After each admixture the water is separated by evaporation, and heat may be applied to hasten this evaporation, but in such manner as to avoid risk of the materials igniting as they become dry. After the first drying operation the material, in a state of powder, is again mixed with saltpeter solution, and it is afterwards again dried as before, and so for three or more times, should it be considered desirable to divide the operation of incorporating the saltpeter into so many operations. When the incorporation of the saltpeter is complete, it only remains to finish the powder for use by ordinary methods. It may be compressed into cakes or prisms, dried, broken up, and granulated in the usual manner.
By this method the dangerous process of grinding the powder after it has been rendered explosive by the addition of the saltpeter may be altogether avoided; or if in any case it should be considered advisable to resort to a grinding process after the materials have been mixed in the manner above described, the danger would be much less than at present, because of the lessened time during which the grinding would be continued.
The carbonaceous matter may also be submitted without risk to a grinding operation after the sulphur has been incorporated with it and before the saltpeter is added.
Although our invention is mainly intended for the manufacture of gunpowder from the ordinary ingredients, it is also applicable to the manufacture of like compounds in which the saltpeter is replaced by nitrate of soda or other salt capable of furnishing the oxygen to the carbonaceous matter and sulphur.
In the preparation of the cotton or vegetable fibre, liquid hydrochloric acid may be employed; but the use of the gas, as herein described, is preferable.
Having thus particularly described and ascertained the nature of our said invention and the manner of performing the same, we declare that what we claim is—
1. As an improvement in the manufacture of gunpowder, the method described of incorporating the sulphur with carbonaceous matter, which consists in dissolving the sulphur in bisulphide of carbon, impregnating the carbonaceous matter with the solution so obtained, and separating the bisulphide of carbon by evaporation, substantially as set forth.
2. As an improvement in the manufacture of gunpowder, the method described of incorporating the sulphur and saltpeter or equivalent salt in the carbonaceous matter, which consists in dissolving the sulphur in bisulphide of carbon, impregnating the carbonaceous matter with the solution so obtained, separating the solvent by evaporating; also impregnating the carbonaceous matter with saltpeter or equivalent salt in solution, and separating the solvent by evaporation, substantially as set forth.
3. The hereinbefore described method of manufacturing gunpowder, which consists in treating cotton or equivalent vegetable fibre with hydrochloric acid (either gaseous or liquid) to obtain carbonaceous matter with the sulphur and saltpeter, substantially as set forth.
From Kept. H. M. Insp. Exp., p. 44; 1885, we learn that an explosion took place in a factory in which gunpowder was being made by Mr. Nordenfeldt's process. The accident was wholly due to carelessness, but the inspectors found that the presence of bisulphide of carbon in powder tends to sensibly lower the point of ignition.
U. S. Letters Patent No. 359289, March 15, 1887, have been granted to Edward Schultze, of Darmstadt, Germany, in accordance with the following specification:
The improvements in the manufacture of gunpowder and similar explosives consist in the composition and combination of three kinds of materials—of a nitro-hydrocarburet with pyroxyline, and thirdly, with a nitrate or salt, formed by the union of nitric acid with a base, and furnishing a compound of oxygen and nitrogen. By mixing these three constituents in various proportions I am able to produce an explosive of greater or less force. When this mixture is to be used as gunpowder for shooting purposes, I take a certain amount of the pyroxyline and diminish the rending force of the pyroxyline by adding nitro-hydrocarburets and nitrates; but when I wish to use said mixture as a blasting explosive, for blasting hard rocks or minerals and other blasting purposes, I augment this amount of pyroxyline with a view to producing greater rending force. When burning, these mixtures are free, or nearly, from noxious fumes, residue, and recoil. I instance, as belonging to the hydrocarburets which I employ in my mixtures, common resin or colophony, tar, turpentine, or turpentine oil, after having treated them with nitric acid. I instance, as belonging to the pyroxylines which I employ, nitro-cellulose (cotton or wood, or any vegetable fibre). I include the different varieties of pyroxyline, and instance the form commonly called gun-cotton. I instance as nitrates those of baryta, potassium or sodium, lime and ammonium. By different combinations of these constituents I am able to produce every class of explosives suitable for all purposes. I can use them, for instance, in the place of dynamite, for blasting hard rocks or minerals, treating the convenient mixture under hydraulic pressure; or in the place of black gunpowder, for blasting rocks or minerals less hard, or in the bombs and shells of the artillery. I can also employ my explosive as a filling for cartridges to be used in coal mines subject to fire-damp. These cartridges will not ignite the fire, damp, and thus obviate a fruitful cause of accidents. I can also choose another percentage in mixing the three constituents, so that the explosive is then suitable as gunpowder for sporting and military purposes.
I will now give examples of the proportions to be used in preparing explosives according to my invention, but I wish to be understood that they are given as the best proportions with which I am acquainted for carrying my invention into effect, and that I do not limit myself to the precise details given in these examples, as I can advantageously vary the proportions in the same manner as the black gunpowder makers can and do vary their proportions of charcoal, sulphur, and saltpeter to produce explosives suited to various requirements. The proportions hereinafter given are by weight. A powder suitable for sporting purposes can be made according to my invention by mixing twelve parts of nitro-tar, or colophony, or turpentine, or turpentine oil, or mixtures of them, with sixty to eighty parts of pyroxyline, sixty to eighty parts of nitrate of baryta, and eight to ten parts of nitrate of potassium.
This mixture is prepared and granulated in the well known manner prevalent in making black gunpowder. I may add some binding material or not, and the grains of the finished powder may be coated or not with substances fit for this purpose, such as paraffine, resin, or collodion.
Not more than five-eighths of this gunpowder for sporting purposes thus produced should be used in the place of the quantity of black gunpowder that is generally used for this purpose. The propelling force of the sporting powder thus produced is excellent, and the rending force is not greater than that of black gunpowder, and it is free or nearly free from objectionable fumes, residue, and recoil.
A good gunpowder for rifles is produced by mixing ten parts of nitro-tar, colophony, turpentine, or turpentine oil, or mixtures of them, with two hundred and eighty to three hundred parts of pyroxyline, one hundred to one hundred and twenty parts of nitrate of baryta, forty to fifty parts of nitrate of potassium, and about ten parts of sulphur.
This mixture is to be granulated in the same manner as the sporting gunpowder, and should be employed in quantities of about two-fifths the weight of the quantity of black gunpowder used for analogous purposes—such, for instance, as that for military rifles. The finished powder may be coated or not, as mentioned with respect to the sporting powder.
My blasting explosive, suitable for use in blasting mild rocks or minerals, has a little proportion of pyroxyline. I may also add to this explosive a quantity of sulphur.
The proportion of the materials may with advantage be about ten parts each of pyroxyline and sulphur, fifteen parts of nitro-hydrocarburets, and seventy -five parts of saltpeter. The greater the proportion of pyroxyline the greater will be the power of the explosive produced, so that when an explosive is required for blasting hard rocks or minerals, the proportion of pyroxyline should and can be increased to suit the purpose for which it is required.
Having fully described my invention, what I desire to claim, and secure by letters patent, is—
The composition, consisting of a nitro-hydrocarburet (such as nitrocolophony, tar, turpentine, or turpentine oil), and of pyroxyline, and of nitrates or salts furnishing oxygen in combination with nitrogen, for shooting and blasting purposes, substantially as described.
According to the Army and Navy Gazette, 23, 673; August 13, 1887, a series of trials has taken pliace at the Middlewick Ranges, Colchester, to test the relative merits of the Government cartridges, as loaded for the Enfield-Martini rifle, and others filled with a newly invented smokeless powder, which has been patented by Messrs. Johnson and Borland. The trial was carried out with a Gardner gun. The first trials consisted in firing 40 rounds of Government ammunition, so as to foul the barrel, and then 10 shots from the dirty barrel to test the accuracy. Although the gun had been well "laid" before the firing of the 10 shots, only 4 at 800 yards hit the target. The barrel was found to be very foul. The same number of shots were then fired with the "Johnson-Borland powder," with the result that in the last 10 of 50 rounds 8 struck the centre of the target. Then the barrels were inspected and compared and found comparatively clean. Indeed, once passing through the cleaning rod removed all residue, whereas it took 7 damped tows to clean the barrel in which the black had been fired. Trials for speed were then made, 40 rounds being fired in 5- seconds. It was found that in consequence of the strain of the new powder being so small, the handle of the gun could be revolved with so much ease that the gun in rapid firing was not put out of position. The explosive force of the Government ammunition was such as to necessitate much more power being exerted in revolving the crank handle—a serious defect—whilst at the same time the "kick" was much greater. Besides this, the smoke from the Government ammunition was such that, after firing 20 rounds rapidly, the smoke accumulated so as to prevent No. I seeing through it; whereas with the new powder it was quite possible to see the bull's-eye at any time during the rapid firing. The velocity of the Government ammunition in the Enfield-Martini rifle is 1570 feet per second, which is the highest of any arm in the European service. With the new powder, 1800 feet per second has been arrived at. The experiments at Colchester show that the days are approaching when a smokeless explosive is likely to take the place of the present powder.
German Letters Patent No. 37631, October 14, 1885, have been granted to Friedr. Gaens, of Hamburg, for a gunpowder without sulphur, but which contains an ammonium salt, which will give rise to the formation of a potassium amine which is to be converted temporarily, at a higher temperature, into the explosive potassium nitride. (Dingl. Poly. Jour. 263, 152: 1887.)
The Scientific American, p. 177, March 19, 1887, under the title Improved Gunpowder, states that A. H. Durnford has patented a process for making a soft charcoal which shall have an extremely low density, a low point of ignition, and slight hygroscopic properties, and which will produce a gunpowder possessing great energy and propelling power combined with moderate pressures when fired in a gun. The novelty consists in using charcoal made from cork by subjecting the cork to destructive distillation in cylinders at such a temperature as will produce the desired result. The gunpowder consists, first, of saltpeter and cork charcoal in the proportions of 80 to 20 respectively; second, of saltpeter, cork charcoal and sulphur, the latter being in proportions varying from 1 to 10 per cent. It is claimed that this powder is comparatively smokeless and non-hygroscopic.
It is now a well known fact that when compressed gun-cotton, dynamite, or other high explosives are freely exposed upon a metal plate and detonated, if the plate is sufficiently strong to resist rupture, the explosive leaves a marked and permanent impression upon the plate; the intensity of the impression being, of course, dependent upon the intensity and amount of the explosive used. This is not surprising when we recall that Berthelot found that gun-cotton having a density of 1.1 will develop, when in contact, a local pressure of 24,000 atmospheres or 160 tons on the square inch, and if we remember, too, that this enormous pressure is realized in an exceedingly brief space of time. The effect may of course be enhanced if the explosive be tamped with earth, water, etc. But, as Cooke has so clearly shown in his essay on the "Air as an Anvil," the aerial fluid may serve as a tamp just as the aqueous one does, though not as efficiently.
It is perhaps not so well known a fact that the impression produced by the exploding mass is an almost exact copy of the form of that surface of the explosive which was in contact with the plate of metal. This feature is best observed with compressed gun-cotton, since, as it is a papier-mâché like body, it is possible to shape it as we fancy and to stamp upon its surface such figures and designs as we wish.
The first recorded observation of this phenomenon of which we are aware, is that made by Lieutenant Max Von Forster, of Walsrode, and a translation of his paper may be found in Van Nostrand's Eng. Mag. 31, 113, August 1884. He says that when a piece of compressed guncotton is detonated on a plate of iron, an accurate impression of the form of the under surface of the gun-cotton is produced. Every angle, every projection, and every indentation present in the gun-cotton is impressed on the underlying iron, and he claims that this is due to the fact that the gases acting on the iron have occupied exactly the same space and no more than the solid explosive previously occupied, and thus transferred its form, and hence he concludes that only the gases evolved by the very undermost layers of gun-cotton act on the iron, while the others are lost.
In Van Nosirand's Eng. Mas;. 32, 1, January 1S85, we have given an illustration of similar impressions which we had observed previous to meeting with Von Forster's paper, and we advanced the opinion there, and subsequently in our Notes, that it was due to projection, the residual gun-cotton being driven into the metal by the explosion of a portion of the original mass, just as any other resisting body interposed in the path of the explosive wave would have been. Of course we are met here by the difficulty that this hypothesis implies (1) that the pressure exerted upon the residual mass of gun-cotton is transmitted more rapidly than the explosive reaction is propagated within the mass, and (2) it implies also a great rigidity or coherency for this mass. The last condition requires that which is a property of masses of matter when moving at high velocities, as in the well known candle experiment, and in the cutting of steel by soft iron, and the like. The difficulties presented in the first condition do not seem so great as those in Lieutenant Von Forster's hypothesis.
Some months subsequent to this, Commander T. F. Jewell, U. S. N., read a paper before the American Association for the Advancement of Science, on "the apparent resistance of a body of air to a change of form under sudden compression," and presented as an example of this phenomenon an iron plate upon which a disk of gun-cotton had been detonated. The letters U. S. N. and the figures 1884 had been indented in the surface of the gun-cotton, and similar letters and figures were found indented in the plate. He held that this was due to the fact that the air enclosed in the letters and figures, under the sudden and enormous pressure to which it was subjected, acted like a hard body and was thus driven into the iron. This paper appears in the Proc. American Association 34, Si; 1886.
In a later pamphlet (Berlin, 1886) Von Forster again states that the gases generated by the detonation of the gun-cotton have, in the first instant, and as long as they exert their maximum force, the exact form and occupy the same space as was occupied by the gun-cotton before detonation, and thus they produce an exact impression of the surface of the gun-cotton in contact with it. He also says that the suddenness with which the power is exerted is shown by placing a leaf between the gun-cotton disk and the iron, for, after detonation, the whole frame or skeleton of the leaf will be found raised upon the iron. He explains that this is due to the larger as well as the smaller ribs of the leaf protecting the underlying parts of the iron, while the thinner parts between could not yield such protection, and under them the impression is deeper.
This was the condition of the subject when we again took it up experimentally in 1886. We first detonated gun-cotton disks upon which the figures and letters were indented, and obtained impressions on the plates in which these were also indented. Next we used disks having raised letters and figures, and obtained impressions in which these were raised. Next we cut deep channels in the disks, of various forms, taking care that they always communicated with the outer air so that there would be no air confined in them, and again these indentations were exactly reproduced in the iron. Next we filled the indented letters and figures, in disks such as Jewell used, with paraffine and with vaseline, so that the material was flush with the surface of the disk, and on detonation the letters' and figures were found to have been obliterated. Next we struck, with stamps, the same letters and figures in an iron plate. This plate was laid face downwards on another iron plate and a lettered gun-cotton disk placed on top and detonated. The result was that while the gun-cotton disk produced the usual indented letters on the back of the top plate of iron, the top plate in whose letters and figures air was also confined and which was subjected to the same blow, produced raised letters and figures on the bottom plate on which it rested. These last three experiments certainly seem to prove that the air has nothing to do with this action. Again, when we consider how enormous the pressure is to which this air is subjected we must believe that, no matter how suddenly the force is applied, the air must undergo some compression, yet we find that the indentations in the iron are often nearly as deep as those in the gun-cotton.
In considering Von Forster's hypothesis, we are willing to admit that the gases at the time of detonation possess the exact form and occupy the same space as the gun-cotton from which they are formed, if the change takes place instantaneously. But it does not; in fact, it occupies so appreciable a period of time that the rate of propagation of the detonation in it has been measured. Apart from this, and even granting it, it will be observed that Von Forster does not explain how the impression is to be produced by the gas. If the gas moves as a solid body, then the impressions should be the reverse of what we get.
From our experiments we are the more strongly convinced that the effect is a purely ballistic one, and that while the base of the guncotton, or its products, are projected as a whole against the plate, where the intervening spaces are the greatest there we have the greatest effect of impact, and consequently the greatest indentation. This is true in the leaf experiment, which has been exquisitely reproduced. The varying thicknesses of the leaf vary the distances through which the material is projected, and hence the form and texture are reproduced in the impression.
These experiments were described before the Am. Assn. Ad. Sci. in August, 1887, and the plates exhibited there have been very accurately and beautifully represented in the Sci. Am. 57, 223, October 8, 1887; but the editorial description is inaccurate in some particulars. In the same paper are illustrations of the application of gun-cotton for testing the resistance of metals to shocks, as described in these Proceedings. It should be stated that this method gives a means for revealing the inner structure of metals in masses such as we have never before possessed.
A new way of utilizing dynamite has been lately devised by a French military engineer, M. Bonnetond. He uses the expansive force to drive out, for a brief period, the water from portions of wet ground in which foundations are to be made. The method is now in practice in the construction of a fortified enceinte at Lyons. A hole is first bored 10 or 12 feet and about 1 ½-inches wide in the wet ground. Into this is passed a string of cartridges of dynamite, which is then exploded. The water is thus driven far out beyond the sides of the cavity, over a yard wide, which is produced, and does not reappear till after half an hour at least. The workmen thus have time to clear the cavity and introduce quickly-setting concrete. When the water returns it cannot injure the foundation. A rapid rate of progress is realized by this method. (Nature, 36, 564; 1887.)
The Boston Globe, July 22, 1887, notes that the balloon department of the German army is experimenting with a view to trying the destructive effect of dynamite hurled down upon forts from a balloon. In the Sci. Am. p. 181, March 19, 1887, W. Maxwell Maynard proposes that large fire balloons, to which a charge of dynamite is attached, be sent up among the rain clouds and discharged there in order to precipitate a rainfall in dry weather.
A new method of blasting without explosives has been recently introduced by Dr. Kosman, and is described in Jour. Inst. Civ. Eng. 87, 41. Zinc powder and sulphuric acid are contained in a glass cartridge, by breaking which the two substances are brought in contact and hydrogen is rapidly evolved. A pressure of about 37,000 atmospheres is obtained, although, perhaps, with hardly sufficient rapidity to justify the use of the term explosion. (Engineering, 43, 67, Jan. 21, 1887.)
A. Cavazzi, Gazzetta Chimica lialiana, in studying the reduction of potassium nitrate by various substances, has found that a mixture of equal parts of the nitrate and sodium hypophosphite detonates violently when heated to about the fusing point of the mixture. Other proportions yield explosive mixtures, but the above are the best. (Sci. Am. p. 181, March 19, 1887.)
H. N. Warren states in the Chemical Ne7us 55, 289, June 24, 1887, that he has probably obtained "Fluoride of Nitrogen" or fluoramide, by passing an electric current from seven ferric chloride batteries through a concentrated solution of ammonium fluoride. After a lapse of a short time, several drops, of oily consistence, were observed attached to the negative plate. On becoming connected with the positive, a thin gold wire, these drops exploded with great violence. The compound is undoubtedly highly unstable, being at once decomposed in contact with glass, silica, or organic matter, thus rendering the analysis one of considerable risk. Its explosive violence is even greater than that of the chloramide, and it is also prone to spontaneous decomposition.
There was recently a prosecution, before one of the Prussian courts, of the agent of a banking house in Berlin, for jeopardy caused to a train of railroad cars. The main question was whether fuming nitric acid could, under the circumstances, occasion spontaneous ignition, which, after hearing the testimony of the court's expert chemist, Dr. Jeserich, was decided in the affirmative. The agent had sent ten kilos (22 pounds) of fuming nitric acid from Berhn, intended for some point in Bavaria, per railroad. The acid was contained in a strong stone jar, tightly closed by a stone stopper and cement. The whole was packed in straw within a wooden case. Since such corrosive and dangerous liquids would not be transported by railroad as express freight, the contents of the box were represented to be clothing, and by this means the concealed acid was sent by a passenger train. During the journey, and when near Butterfeld station, the car containing the express freight was discovered to be on fire.
Before the flames had made serious progress, the car was uncoupled and switched off on a side track, and the fire extinguished with comparatively slight damage, and no person was injured. Examination showed that the jar had leaked, and the acid had come in contact with a roll of woolen cloth, whereby the latter was set on fire. Dr. Jeserich gave it as his opinion that all woolen goods and all hair of animals, horn, etc., have the property of igniting spontaneously when coming in contact with fuming nitric acid; and he stated that all new explosives, about which there had been so much said and written lately, such as roburite, melanite, etc., are produced by the action of nitric acid on hair and wool. Herr Lack, the agent who made the misrepresentation about the acid, was condemned to two months imprisonment. (Sci. Am. 57, 260; 1S87, Abstr. All Vers. Fresse, Berlin.)
When preparing hypochlorous anhydride by the usual process, A. Mermel used liquid methyl chloride as a refrigerant instead of snow and salt. A violent explosion took place, the apparatus being destroyed and the assistant in charge had the lobe of his right ear torn. This catastrophe is ascribed to the vapors of the two liquids coming in contact. (Chemical News 55, 249, May 27, 1887, Abstr. Bull. Soc. Chim. 47, March 5, 1887.)
Scribner's Magazine, 2, 197-221, August 1887, contains an interesting article by N. S. Shaler on the "Instability of the Atmosphere," in which the destructive effects produced by a sudden rush of gas are well described, and illustrated by numerous photographs. In speaking of the tornado he says that in its path over the surface, the circling movement of the writhing air and the sucking action of the partial vacuum in the central portion of the shaft combine to bring about extreme devastation. On the outside of the whirl the air, which rushes in a circling path toward the vortex, overturns all movable objects, and in the centre these objects, if they are not too heavy, are sucked up as by a great air-pump. Thus the roofs of houses, bodies of men and animals, may be lifted to great elevations, until they are tossed by the tumultuous movements beyond the limits of the ascending currents and fall back upon the earth. Where the centre of the whirlwind passes over a building, the sudden decrease in the pressure of the outer air often causes the atmosphere which is contained within the walls suddenly to press against the sides of the structure, so that these sides are quickly driven outward as by a charge of gunpowder.
It is not unlikely that the diminution of pressure brought about by the passage of the interior of the whirl over a building may be about as much as is indicated by the fall of four inches in the barometer. This is equivalent to a change in the pressure amounting to about 300 pounds to the square foot. This force operates to burst out the walls of a building. It is not improbable that the diminution of pressure may be much greater than this, but the amount named is sufficient to produce many of the effects noted.
These effects may be compared with those produced by the discharge of heavy ordnance or the blasts from high explosives.
G. Masson, Paris, announces, in June 1887, the publication of Les nouveaux explosifs et la fortification, by le commandant Mougin.