28 rerort—1890. 
time actively engaged upon the production of a suitable powder for heavy 
guns, directed their attention, not merely to an alteration of the propor- 
tions of the ingredients, but also to a modification in the character of char- 
coal employed ; the eventual result was the production of a new pris- 
matic 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 super- 
heated 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 com- 
paratively gradual and long-sustained. The products of its explosion are 
simple ; asthe powder contains saltpetre in large proportion relatively to 
the sulphur and charcoal, these become fully oxidised, and a relatively very 
large amount of water-vapour is produced, partly because of the com- 
paratively 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 advan- 
tage, 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 110-ton gun, from which shot of about 1,800 lb. weight are propelled 
by a powder-charge of 960 lb. Brown powder has therefore been modi- 
fied in composition 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 employment becomes greatly limited 
when, aftera 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 decom- 
