12 Sir Frederick Abel [Jan. 31, 



black powder, but also because the very sliglilly cbarred wood or straw 

 used in the brown powder is much richer in hydrogen than black 

 charcoal, and therefore furnishes by its oxidation a considerable 

 amouut 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 denseness to 

 that of black powder, it certainly disperses much more rapidly, a 

 difference which is probably due to the speedy absorption, 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 advantage 

 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 lbs. 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 intermediate 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 compara- 

 tively 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 efficieocy 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 

 attention 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 engage- 

 ments has also created a demand, the apparent urgency of which 

 has been increased by various circumstances, for a smokeless powder 

 suitable for field artillery and small arms. 



The properties of ammonium nitrate, of which the products of de- 

 composition by heat are, in addition to water-vapour, entirely gaseous, 



