Feb, 6, 1890] 



NA TURE 



329 



of black powder could be as well and even more readily secured 

 by the thorough blending or mixing together of batches pre- 

 senting some variation in I'egard to density, hardness, or other 

 features, as by aiming at an approach to absolute uniformity in 

 the characters of each individual mass composing a charge. 



At the time that our attention was first actively given to this 

 subject of the modification of the ballistic properties of powder, 

 it had already been to some extent dealt with in the United 

 States by Rodman and Doremus, and the latter was the first to 

 propose the application, as charges for guns, of powder-masses 

 produced by the compression of coarsely grained powder into 

 moulds of prismatic form. In Russia the first step was taken to 

 utilize the results arrived at by Doremus, and to adopt a prismatic 

 powder for use in guns of large calibre. 



Side by side with the development and perfection of the 

 manufacture of prismatic powder in Russia, Germany, and in 

 this country, new experiments on the production of powder- 

 masses suitable, by their comparatively gradual action, for 

 employment in the very large charges required for the heavy 

 artillery of the present day, by the powerful compression of 

 mixtures of more or less finely broken up powder-cake into 

 masses of greater size than those of the pebble, pellet, and 

 prism powders, were actively pursued in Italy, and also by our 

 own Government Committee on Explosives, and the outcome of 

 very exhaustive practical investigations were the very efficient 

 Fossano powder, or foudre progressif, of the Italians, and the 

 boulder and large cylindrical powders known as P- and C^, 

 produced at Waltham Abbey, which scarcely vied, however, 

 with the Italian powder in the uniformity of their ballistic 

 properties. 



Researches carried out by Captain Noble and the lecturer some 

 years ago with a series of gunpowders differing considerably in 

 composition from each other, indicated that advantages might be 

 secured in the production of powders for heavy guns by so modi- 

 fying the proportions of the constituents {e.g. by considerably 

 increasing the proportion of charcoal and reducing the proportion 

 of sulphur) as to give rise to the production of a much greater 

 volume of gas, and at the same time to diminish the heat developed 

 by the explosion. 



These researches served, among other purposes, to throw con- 

 siderable light upon the cause of the wearing or erosive action of 

 powder-explosions upon the inner surface of the gun, which in 

 time may produce so serious a deterioration of the arm as to 

 diminish the velocity of projection considerably, and so affect the 

 accuracy of shooting, a deterioration which increases in extent 

 in an increasing ratio to the size of the guns, in consequence, 

 obviously, of the large increase in the weight of the charges fired. 

 Several causes undoubtedly combine to bring about the wear- 

 ing away of the gun's bore, which is especially great where the 

 products of explosion, while under the maximum pressure, can 

 escape between the projectile and the bore of the gun. The 

 great velocity with which the very highly heated gaseous and 

 liquid (fused solid) products of explosion sweep over the heated 

 surface of the metal gives rise to a displacement of the particles 

 composing it, which increases as the surface becomes roughened 

 by the first action upon the least compact portions of the metal, 

 and thus opposes greater resistance ; at the same time, the 

 effect of the high temperature to which the surface is raised is 

 to reduce its rigidity and power of resisting the force of the 

 gaseous torrent, and lastly some amount of chemical action 

 upon the metal, by certain of the highly heated non-gaseous 

 products of explosion, contributes towards an increase in the 

 erosive effects. A series of careful experiments made by 

 Captain Noble with powders of different composition, and with 

 other explosives, afforded decisive evidence that the material 

 which furnished the largest proportion of gaseous products, and 

 the explosion of which was attended by the development of the 

 smallest amount of heat, exerted least erosive action. 



It is probable that important changes in the composition of 

 powders manufactured by us for our heavy guns would have 

 resulted from those researches, but in the meantime, two 

 eminent German gimpowder manufacturers had occupied them- 

 selves independently, and simultaneously, with the important 

 practical question of producing some more suitable powder for 

 heavy guns than the various new forms of ordinary black 

 powder, the rate of burning of which, especially when confined 

 in a close chamber, was, after all, reduced only in a moderate 

 degree by the increase in the size of the masses, and by such 

 increase in their density as it was practicable to attain. The 



German experimenters directed their attention not merely to the 

 proportions in which the powder ingredients are employed, but 

 also to a modification in the character of charcoal, and the 

 success attending their labours in these directions led to the 

 practically simultaneous production, by Mr. Heidemann at the 

 Westphalia Powder Works, and Mr. Diittenhofer at the Rott- 

 weil Works neari Hamburg, of a prismatic powder of cocoa- 

 brown colour, consisting of saltpetre in somewhat higher 

 proportion, of sulphur in much lower proportion, than in 

 normal black powder, and of very slightly burned charcoal, 

 similar in composition to the charcoal {charbon roux) which 

 Violette, a French chemist, first produced in 1847 by the action 

 of superheated steam upon wood or other vegetable matter, and 

 which he proposed for employment in the manufacture of 

 sporting powder. These brown prismatic powders (or "cocoa- 

 powders," as they were termed from their colour), are dis- 

 tinguished from black powder not only by their appearance, but 

 also by their very slow combustion in open air, by their com- 

 paratively gradual and long-sustained action when used in guns, 

 and by the simple character of their products of explosion as 

 compared with those of black powder. As the oxidizing in- 

 gredient, saltpetre, is contained, in brown or cocoa powder, in 

 larger proportion relatively to the oxidizable components, sulphur 

 and charcoal, than in black powder, these become fully oxidized, 

 while the products of explosion of the latter contain, on the 

 other hand, larger proportions of unoxidized material, or only 

 partially oxidized products. Moreover, there is produced upon 

 the explosion of brown powder a relatively very large amount 

 of water-vapour, not merely because the finished powder con- 

 tains a larger proportion of water than black pDwder, but also 

 because the very slightly charred wood or straw used in the 

 brown powder is much richer in hydrogen than black charcoal, 

 and therefore furnishes by its oxidation a considerable amount 

 of water. The total volume of gas furnished by the brown 

 powder (at 0° C. and 760 mm. barometer) is only about 200 

 volumes per kilogramme of powder, against 278 volumes, 

 furnished by a normal sample of black powder, but the amount 

 of water-vapour furnished upon its explosion is about three 

 times that produced from black powder, and this would make 

 the volume of gas and vapour developed by the two powders 

 about equal if the heat of its explosion were the same in the 

 two cases ; the actual temperature produced by the explosion 

 of brown powder, is, however, somewhat the higher of 

 the two. 



Although the smoke produced upon firing a charge of brown 

 powder from a gun appears at first but little different in dense- 

 ness to that of black powder, it certainly disperses much more 

 rapidly, a difference which is probably due to the speedy absorp- 

 tion, by solution, of the finely divided potassium salts by the 

 large proportion of water-vapour distributed throughout the so- 

 called smoke. 



This class of powder was substituted with considerable advan- 

 tage for black powder in guns of comparatively large calibre ; 

 nevertheless it became desirable to attain even slower or more 

 gradual action in the case of the very large charges required for 

 guns of the heaviest calibres, such as those which propel shot of 

 about 2000 pounds weight. Accordingly, the brown powder has 

 been modified in regard to the proportions of its ingredients to- 

 suit these conditions, while, on the other hand, powder inter- 

 mediate with respect to rapidity of action between black pebble 

 powder and the brown powder, has been found more suitable 

 than the former for use in guns of moderately large calibre. 



The recent successful adaptation of machine guns and com- 

 paratively large quick-firing guns to naval service, more especially 

 for the defence of ships against attack by torpedo boats, &c. , 

 has rendered the provision of a powder for use with them, 

 which would produce comparatively little or no smoke, a matter 

 of very considerable importance, inasmuch as the efficiency of 

 such defence must be greatly diminished by the circumstance 

 that, after a very brief use of the guns with black powder, the 

 objects against which their fire is destined to operate, become 

 more or less completely hidden from those directing them, by 

 the dense veil of powder-smoke produced. Hence much atten- 

 tion has been directed during the last few years to the production 

 of smokeless, or nearly smokeless powders for naval use in the 

 above directions. At the same time, the views of many military 

 authorities regarding the importance of dispensing with smoke 

 in land engagements has also created a demand, the apparent 

 urgency of which has been increased by various circumstances,. 



