September 4, 1890] 



NATURE 



441 



particular gunpowder, when employed under like conditions, 

 demands not merely identity in regard to composition, but also 

 identity in form, size, density, and structure of the individual 

 masses of which a charge consists. To approach the practical 

 realization of this view, equal quantities of one and the same 

 mixture of ingredients, presented in the form of powder of 

 uniform fineness and dryness, must be submitted to a particular 

 pressure, for a fixed period, in moulds of uniform size, the 

 surrounding conditions and subsequent manufacturing processes 

 being as nearly as possible alike. Practical experience has however 

 shown that uniformity in the ballistic properties of black powder 

 can be even more readily secured by the thorough blending or 

 mixing together of different products of manufacture, presenting 

 some variations in regard to size, density, hardness, or other 

 features, than by aiming at an approach to identity in the charac- 

 ters of the individual grains or masses. 



When our attention was first actively directed to the modi- 

 fication of the ballistic properties of powder, the subject had 

 already been to some extent dealt with, in the United States, 

 by Rodman and Doremus, and the latter had proposed the 

 employment, in heavy guns, of charges consisting of large 

 pellets of prismatic form. While this prismatic powder, which 

 was first used in Russia, was being perfected, and extensively 

 applied there as well as in Germany and England, the produc- 

 tion of powder-masses more suitable, by the comparatively 

 gradual nature of their explosion, for the very large charges 

 required for the heavy artillery of the present day, was actively 

 pursued in Italy, and by our own Government Committee on 

 Explosives ; the outcome of exhaustive practical investiga- 

 tions being the very efficient Fossano powder, or poudre pro- 

 gressif oi the Italians, and the boulder- and large cylindrical- 

 powders produced at Waltham Abbey. 



Researches carried out by Captain Noble and myself, some 

 years ago, with a series of gunpowders, presenting considerable 

 differences in composition, indicated that decided advantages 

 might be Fecured, for heavy guns especially, by the employment 

 of such a powder as would furnish a comparatively very large 

 volume of gas, its explosion being at the same time attended by 

 the development of much less heat than in the case of ordinary 

 black powder. In the course of these researches much light 

 was thrown upon the causes of the wearing or erosive action of 

 powder-explosions upon the inner surface of the gun, an action 

 which, especially in the larger calibres of artillery, produces so 

 serious a deterioration of the arm that the velocity of projection 

 and accuracy of shooting suffer considerably, the wear being 

 especially great where the products of explosion, while under 

 the maximum pressure, can escape between the projectile and 

 the bore. 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 the surface of the bore, which increases 

 in extent as the latter becomes roughened, and thus opposes 

 greater resistance ; at the same time, the high temperature to 

 which the surface is raised reduces the rigidity of the metal, and 

 its consequent 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. 

 Experiments made upon a large scale by Captain Noble with 

 ])owders of different composition, and with other explosives, 

 have afforded decisive evidence that the explosive agent which 

 furnishes the largest proportion of gaseous products, and the 

 explosion of which is attended by the development of the 

 smallest amount of heat, exerts least erosive action. 



Some eminent German gunpowder-manufacturers, who were 

 at this time actively engaged upon the production of a suitable 

 powder for heavy guns, directed their attention, not merely to 

 an alteration of the proportions of the ingredients, but also to 

 a modification in the character of charcoal employed ; the 

 eventual result was the production of a new prismatic powder, 

 composed of saltpetre in somewhat higher proportion than in 

 normal black powder, and of a very slightly-burned charcoal of 

 reddish-brown colour, quite similar to the charbon roux which 

 Violette produced about forty years ago for use in sporting- 

 powder, by the action of superheated steam upon wood or 

 other vegetable matter. This brown prismatic powder (or 

 "cocoa powder") differs from black powder not merely in 

 colour: it burns very slowly in the open air, and in guns its 

 action is comparatively gradual and long-sustained. The pro- 

 ducts of its explosion are simple. As the powder contains salt- 



NO. 1088, VOL. ^2] 



petre in large proportion relatively to the sulphur and charcoal, 

 these become fully oxidized, and a relatively very large amount 

 of water-vapour is produced, partly because of the comparatively 

 high proportion of water in the finished powder, and partly 

 from the large amount of hydrogen in the slightly-charred wood 

 or straw used. The smoke from a charge of brown powder 

 differs but little in volume from that of black powder, but it 

 disperses much more rapidly, owing to the speedy absorption of 

 the finely-divided potassium salts, forming the smoke, by the 

 large proportion of water- vapour through which they are 

 distributed. 



This kind of powder has been substituted, with considerable 

 advantage, for black powder in guns of comparatively large 

 calibre, but it soon became desirable to attain even more gradual 

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

 the heaviest calibres, such as the iioton gun, from which shot 

 of about 1800 lbs. weight are propelled by a powder-charge of 

 960 lbs. Brown powder has, therefore, been modified in com- 

 position to suit these conditions ; while, on the other hand, a 

 powder intermediate in rapidity of action between black powder 

 and the brown prism powder has been found more suitable than 

 the former for use in guns of moderately large calibre. 



The importance which machine-guns and comparatively large, 

 quick-firing guns have assumed in the armament of ships has 

 made it very desirable to provide a powder for them which will 

 produce comparatively little or no smoke, as their efficient em- 

 ployment becomes greatly limited when, after a very few rounds 

 rapidly fired, with black powder, the objects against which it is 

 desired to direct the fire, are more or less completely hidden by 

 the interposed smoke. Hence much attention has of late been 

 directed to the production of smokeless, or nearly smokeless, 

 powders for naval use. At the same time, the views of many 

 military authorities regarding the importance of dispensing with 

 smoke in engagements on land have also created a demand for 

 smokeless powders suitable for field-artillery and for small-arms. 



The properties of ammonium-nitrate, of which the products 

 of decomposition by heat are, in addition to water-vapour, 

 entirely gaseous, have rendered it a tempting material to those 

 who have striven to produce a smokeless powder ; but its 

 deliquescent character has been a formidable obstacle to its 

 application as a component of a useful explosive agent. By 

 incorporating charcoal and saltpetre in particular proportions 

 with ammonium-nitrate, F. Gaus recently claimed to have pro- 

 duced an explosive material free from the hygroscopic character 

 common to other ammonium-nitrate mixtures, and furnishing 

 only permanently gaseous and volatile, or smokeless, products of 

 explosion. These anticipations were not realized, but they led 

 the talented German powder-maker, Mr. Heidemann, to produce 

 an ammonium-nitrate powder possessing remarkable ballistic 

 properties, and producing comparatively little smoke, which 

 speedily disperses. It yields a very much larger volume of gas 

 and water-vapour than either black or brown powder, and is 

 considerably slower in action than the latter ; the charge re- 

 quired to produce equal ballistic results is less, while the 

 chamber-pressure developed is lower, and the pressures along 

 the chase of the gun are higher, than with brown powder. No 

 great tendency is exhibited by it to absorb moisture from an 

 ordinarily dry, or even somewhat moist, atmosphere, but it 

 rapidly absorbs water when the hygroscopic condition of the air 

 approaches saturation, and this greatly restricts its use. 



About five years ago reports began to reach us from France 

 of the attainment of remarkable results with a smokeless powder 

 employed with the repeating or magazine rifle then in course of 

 adoption for military service, and of marvellous velocities ob- 

 tained by the use of this powder, in specially constructed 

 artillery of great length. As in the case of the explosive agent 

 called Melinite, the fabulously-destructive effects of which were 

 much vaunted at about the same time, the secret of the nature 

 of this smokeless powder was well preserved by the French 

 authorities ; it is now known, however, that more than one 

 smokeless explosive has succeeded the original, and that the 

 material at present in use with the Lebel repeating rifle belongs 

 to a class of nitro-cellulose or nitro-cotton preparations, of which 

 several have been made the subject of patents in England, and 

 of which varieties are also being used in Germany and other 

 countries. 



A comparison between the chemical changes attending the 

 burning or explosion of gunpowder, and of the class of nitro- 

 compounds represented by gun-cotton, at once explains the 

 cause of the production of smoke by the former, and of the 



