1890.] on Smokeless Explosives. 13 



have rendered it a tempting material to work upon in the hands of 

 those who have striven to produce a smokeless powder, but its deliques- 

 cent character has been the chief obstacle to its application as a com- 

 ponent of an explosive agent susceptible of substitution for black 

 powder for service purposes. 



A German chemical engineer, F. Gans, conceived that, by incor- 

 porating charcoal and saltpetre with a particular proportion of 

 ammonium nitrate, he had produced an explosive material which did 

 not partake of the hygroscopic character common to other ammonium- 

 nitrate mixtures, and that, by its explosion, the potassium in the 

 saltpetre formed a volatile combination with nitrogen and hydrogen, a 

 potassium amide, so that, although containing nearly half its weight of 

 potassium salt, it would furnish only volatile products. The views of 

 Mr. Gans regarding the changes which his so-called amide powder 

 undergoes upon explosion were not borne out by existing chemical 

 knowledge, while the powder compounded in accordance with his views 

 proved to be by no means smokeless, and was certainly not non-hygro- 

 scopic. Mr. Heidemann has, however, been successful, by modifications 

 of Gans's prescription and by application of his own special experience 

 in j)owder-manufacture, in producing an ammonium nitrate powder 

 possessed of remarkable ballistic properties, furnishing comparatively 

 little smoke, which speedily disperses, and exhibiting the hygroscopic 

 characteristics of ammonium nitrate preparations in a decidedly less 

 degree than any other hitherto prepared. The powder, while yielding 

 a very much larger volume of gas and water-vapour than black or 

 brown powder, is considerably slower 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 in the case of brown powder. 



The ammonium nitrate powder contains, in its normal, dried 

 condition, more water than even brown powder ; it does not exhibit 

 any great tendency to absorb moisture from an ordinarily dry or even 

 a somewhat moist atmosphere, but if the amount of atmospheric 

 moisture approaches saturation, it will rapidly absorb water, and 

 when once the process begins it continues rapidly, the powder masses 

 becoming speedily quite pasty. The charges for quick-firing guns 

 are enclosed in metal cases, in which they are securely sealed up ; the 

 powder is therefore prevented from absorbing moisture from the 

 external air, but it has been found that if the cartridges are kept for 

 long periods in ships' magazines, in which, Irom their position 

 relatively to the ship's boilers, the temperature is more or less 

 elevated, sometimes for considerable periods, the expulsion of water 

 from some portions of the powder-masses composing the hermetically 

 sealed charge, and its consequent irregular distribution, may give rise to 

 a want of uniformity in the action of the powder, and to the occasional 

 development of high pressures. Although, therefore, this ammonium- 

 nitrate powder may be regarded as the first successful advance towards 

 the production of a comparatively smokeless artillery-powder, it is 



