THERMO-OHEMICAL RESEARCHES. 535 



On the other hand, the law of ordinary combustion answers 

 to a system in which heat is to a great extent lost by radiation, 

 conduction, expansion, contact with surrounding bodies, etc., 

 with the exception of the very small quantity indispensable for 

 raising the adjacent parts up to the temperature of combustion ; 

 the excess of heat here tends to reduce itself to zero, and con- 

 sequently the excess of the velocity of translation of the mole- 

 cules, that is to say, the excess of pressure of the inflamed 

 section on the adjacent section. 



After having shown in Book I. the general characteristics of 

 explosive phenomena, it is now desirable to define the funda- 

 mental circumstance which determines their energies, that is, 

 the heat liberated by chemical transformation. This is the 

 object of Book II. 



BOOK II. 



Any theoretical study of explosives demands a general 

 knowledge of the principles of thermo-chemistry, namely, of its 

 methods and of its results ; we have deemed it fitting to sum- 

 marise these notions at the opening of Book II. The reader 

 will there find more especially the description of the author's 

 ordinary calorimeter and of the calorimetric bomb which he 

 used in studying the heat of detonation of a large number of 

 gases. Some extensive tables will be shown in this summary, 

 showing the heat of formation of the principal combinations in 

 various stages, as also the specific heats and densities of the 

 various compounds likely to intervene in the study of explosive 

 substances. 



We have devoted ourselves principally to the heat of forma- 

 tion of those fundamental compounds which help to form these 

 substances, namely, oxygenated compounds of nitrogen and 

 their salts, the hydrogenated compounds of nitrogen, cyanic 

 compounds, carbonated derivatives of nitrogen, nitrogen 

 sulphide, hydrocarbon nitric derivatives, such as nitric ether of 

 alcohol, nitroglycerin, nitromannite, gun-cotton ; the nitrated 

 derivatives, such as nitro-benzene, picric acid, etc. ; the azoic 

 derivatives, such as diazobenzene and mercury fulminate. We 

 have also studied the results derived from the oxacids of 

 chlorine and the explosive oxalates. 



This study, which has been lengthy, difficult, and sometimes 

 even fraught with danger, is almost entirely the result of the 

 author's own personal experiments. 



Hence it has been thought advisable to set down here the 

 amplified statement of methods and results, and thus to place 

 before the readers all the data on which the thermo-chemistry of 

 explosive compounds is based. 



