an effect wlilcb, notwitbstanding the application of devices in the building 

 up of the charge specially directed to the preservation of the gun's bore, 

 have become so serious that, with the enormous charges now iised in our 

 heavy guns, the erosive action on the surface of the bore produced by a 

 single round is distinctly perceptible. As there appeared to be primii 

 facie reasons why the erosive action of powder upon the surface of the 

 bore, at the high temperatures developed, should bo at any rate in part due 

 to its one component sulphur, Noble and Abel have made comparative 

 experiments with powders of the usual composition and with otters in 

 which the proportion of sulphur was considerably increased, the extent of 

 erosive action of the products escaping from the explosion vessel under 

 high 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, contain- 

 ing 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, when larger charges were reached. Other important con- 

 tributions 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 pi'oposeda 

 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 exjDlosive agent, leads us up to a con- 

 sideration 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 Heidel- 

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

 dielectric under examination, exercises a detei'mining 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 guttapercha an increase of elasticity takes place. 



Still greater strides are being made at the present time towards a clearer 

 pei'ception of the condition of matter when particles are left some liberty 

 to obey individually the forces brought to bear upon them. By the dis- 

 charge of high tension electricity through tubes containing highly rarefied 



