ADDRESS. 29 
position 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 am- 
monium-nitrate, I’. Gaus recently ciaimed to have produced 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 real- 
ised, but they led the talented German powder-maker, Mr. Heide- 
mann, 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 required 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 ser- 
vice, and of marvellous velocities obtained by the use of this powder, in 
specially constructed artillery of great length. As in the case of the explo- 
sive agent called Mélinite, the fabulously-destructive effects of which were 
much vaunted at about the same time, the secret of the nature of this smoke- 
less 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 pre- 
parations, 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 repre- 
sented by gun-cotton, at once explains the cause of the production of 
smoke by the former, and of the smokelessness of the latter. Whilst 
the products of explosion of the nitro-compounds consist exclusively of 
_ gases and of water-vapour, gunpowder, being composed of a large propor- 
tion of saltpetre, or other metallic nitrate, mixed with charred vege- 
table matter and variable quantities of sulphur, furnishes products of 
_which over 50 per cent. are not gaseous, even at high temperatures, and 
which are in part deposited as a fused solid—which constitutes the 
