.SYA' WILLIAM SIEMENS, F.R.S. 353 



sulphur, XoNe and Abel have made comparative experiments with 

 powders of usual composition and with others in which the pro- 

 portion of sulphur was considerably increased, the extent of erosive 

 action of the products escaping from the explosion vessel under 

 hi.n-h tension being carefully determined. With small charges a 

 particular powder containing no sulphur was found to exert very 

 little erosive action as compared with ordinary cannon powder ; 

 but another powder, containing the maximum proportion of 

 sulphur tried (15 per cent.), was found equal to it under these 

 conditions, and exerted very decidedly less erosive action than it, 

 \vlu-n larger charges were reached. Other important contributions 

 to our knowledge of the action of fired gunpowder in guns, as well 

 as decided improvements in the gunpowder, manufactured for the 

 very heavy ordnance of the present day, may be expected to result 

 from a continuance of these investigations. Professor Carl Himly, 

 of Kiel, having been engaged upon investigations of a similar 

 nature, has lately proposed a gunpowder in which hydrocarbons 

 (precipitated from solution in naphtha) take the place of the 

 charcoal and sulphur of ordinary powder ; this powder has 

 amongst others the peculiar property of completely resisting the 

 action of water, so that the old caution, " Keep your powder dry," 

 may hereafter be unnecessary. 



The extraordinary difference of condition, before and after its 

 ignition, of such matter as constitutes an explosive agent, leads 

 us up to a consideration of the aggregate state of matter under 

 other circumstances. As early as 1776 Alexander Volta observed 

 that the volume of glass was changed under the influence of 

 electrification, by what he termed electrical pressure. Dr. Kerr, 

 Govi, and others have followed up the same inquiry, which is at 

 present continued chiefly by Dr. George Quincke, of Heidelberg, 

 who finds that temperature, as well as chemical constitution of the 

 dielectric under examination, exercises a determining influence 

 upon the amount and character of the change of volume effected 

 by electrification ; that the change of volume may under certain 

 circumstances be effected instantaneously as in flint glass, or only 

 slowly as in crown glass, and that the elastic limit of both is 

 diminished by electrification, whereas in the case of mica and of 

 gutta pcrcha an increase of elasticity takes place. 



VOL. III. A A 



