Dr. R. Hare on the Explosiveness of Nitre. 541 



sidered that without heat there could be no fluidity, heat may 

 be viewed as the sole solvent. As respects the induction of 

 the state requisite to chemical reaction, we may consider the 

 solution in which water is the ostensible agent, or igneous 

 fusion in which it is absent, as the only means of bringing 

 the atoms of solids into the state requisite for chemical reac- 

 tion, through which decompositions and recompositions are 

 effected. 



It is well known that the affinities which prevail among the 

 same set of bodies when liquefied by aqueous solution, may 

 be the opposite of those which they exert when indebted to 

 heat solely for liquefaction. Thus there is scarcely any acid 

 which will not displace silicic or boric acid from alkaline 

 bases when in aqueous solution; yet when salts, consisting in 

 part of the most energetic acids, are fused with silicic or boric 

 acid, decomposition ensues in consequence of the union of the 

 acids last-mentioned, with the bases ignited with them. 



The sulphates, carbonates, or hydrates of potash, soda, 

 and of some other bases, are per se indecomposable at any heat 

 at which their bases cannot be volatilized ; yet the nitrates of 

 the same bases are decomposed at the temperature of incan- 

 descence. It follows, that if a nitrate be exposed to igneous 

 fusion with any substance consisting more or less of hydrogen, 

 carbon, or sulphur, the oxygen of the nitrate will, by form- 

 ing water with the hydrogen, carbonic acid with the carbon, 

 or sulphuric acid with the sulphur, cause the nitrate to be 

 replaced by a hydrate, a carbonate, or sulphate*. 



But as in every atom of nitrate there are, independently of 

 the base, 5 atoms of oxygen, and since to convert hydrogen 

 into water requires 1 atom, to convert carbon into carbonic 

 acid requires 2 atoms, and to effect an analogous change in 

 sulphur requires 3 atoms, it follows, that for every atom of 

 hydrogen there will be 4 atoms of oxygen liberated, for every 

 atom of carbon 3 atoms, and for every atom of sulphur 2 

 atoms. Each atom of oxygen is to the weight of nitrate of 

 potash as 8 to 102; hence there will be by hydrogen nearly 

 32 per cent., by carbon nearly 24 per cent., by sulphur 16 

 per cent, of oxygen evolved to act upon the excess of the con- 

 tiguous combustible matter. Meanwhile it must be recollected 

 that in gum, sugar, starch, and lignin (or fibre of wood, cotton, 

 or linen), both hydrogen and oxygen exist in due propor- 



* The power of decomposing incandescent nitre by aqueous vapour, 

 which was inferred by me to exist in 1845, has since been fully verified by 

 the employment of this vapour by an American chemist, Tilghman, to effect 

 the decomposition of compounds containing potash, or other alkaline bases 

 capable of forming hydrates, per se, indecomposable by heat. (See Note, 

 pages 531, 532.) 



