Intelligence and Miscellaneous Articles. 229 



'■Dr. Hare presumes that no explosion can take place unless the re- 

 agents for producing it are held or brought together at the moment 

 of reaction, by a certain force, either chemical or mechanical. 



Some chemical compounds, such as are formed with fulminic acid 

 or with ammonia, by metallic oxides ; also the chloride of nitrogen 

 and perchloric aether, explode violently without confinement, so as 

 to fracture a plate or saucer, upon which a small quantity may be 

 detonated ; but pulverulent mixtures, such as gunpowder, however 

 powerfully explosive when employed in gunnery or rock- blasting, in 

 open vessels flash without fracturing them, or producing any report. 

 In an exhausted receiver gunpowder is far less explosive than when 

 subjected to atmospheric pressure in an open vessel. Nevertheless, 

 when gunpowder is restrained until the temperature requisite for the 

 appropriate reaction of its ingredients is attained, it exerts a force 

 far exceeding that which the chamber confining it is capable of re- 

 sisting. In this respect it differs from steam, of which, when the 

 temperature of the fire applied is sufficiently high, the explosive force 

 is directly as the pressure immediately before bursting, and this of 

 course is commensurate with the strength of the confining boiler. 



The ingredients of gunpowder, sulphur, charcoal and nitre, to pro- 

 duce the greatest effect, require extreme comminution and intimate 

 intermixture by trituration, and to be so granulated that the flame of 

 the portion first ignited may convey inflammation to the rest through 

 the interstices between the grains. Its superiority over any other 

 mixture of nitre with combustible matter destitute of sulphur, is con- 

 ceived to be due not only to the pre-eminent susceptibility of this 

 substance, of vaporization and inflammation, but likewise to its well- 

 known ability to decompose metallic oxides by attracting botli the 

 metal and oxygen. Since an opinion was expressed in 1845, in the 

 letter above-mentioned to Hays, that the formation of sulphide of 

 potassium is the first step in the process of the explosive reaction of 

 gunpowder, Faraday has alleged the flame of this compound to be, 

 in the case in point, an important instrument in the propagation of 

 fire throughout the mass. 



The hepatic odour of the fumes consequent to the firing of cannon, 

 and likewise of the washings of a gun after the customary service, 

 demonstrate the production of a sulphide. It has been found that a 

 filtered solution of the residue displays, when tested by iron, the red 

 hue which indicates the presence of a sulphocyanide. 



Agreeably however to a qualitative examination, the solid residue 

 of exploded gunpowder consists mainly of nearly equal parts of car- 

 bonate and sulphate of potash, while the gaseous residue is consti- 

 tuted nearly of equal volumes of carbonic acid and nitrogen. Of 

 course the sulphate may arise from the oxidation of sulphide formed 

 at the outset. Notwithstanding that the ingredients of gunpowder 

 are prepared as above stated, confinement is necessary to prevent 

 the grains from being thrown apart and chilled, so as to prevent the 

 propagation of the ignition, through the congeries forming a charge, 

 by means of the flame of the first portions fired. This was fully 

 demonstrated by the exposure of a pile of gunpowder, comprising 



