CHAPTEK II. 



1. CHEMICAL COMPOSITION. 



1. THE composition of the products of explosion can be foreseen 

 whenever the explosive substance contains enough oxygen to 

 transform the elements into stable compounds, and at the 

 highest degree of oxidation, as in the case of nitroglycerin and 

 nitromannite. This limit corresponds also to the maximum 

 thermal effect. It is not always attained in practice, especially 

 by the mixtures which contain potassium nitrate, on account of 

 the rapidity of the chemical and mechanical reactions and of 

 the cooling. 



The explosive decomposition of certain binary compounds, 

 such as nitrogen sulphide, gives rise also to known products. 



2. On the contrary, when the oxygen does not suffice for 

 total oxidation, or when ternary substances (not containing 

 oxygen), such as diazobenzol, are in question, the products 

 formed generally vary with the conditions of the explosion, 

 temperature, pressure, expansion, mechanical effects, etc. This is 

 also the case with black powder, gun-cotton and potassium picrate. 



Under these circumstances, the composition of the products 

 cannot be determined beforehand, but must be ascertained by 

 special analyses, and for each condition of the reaction. 



3. In this connection, experiments may be given relative to 

 the influence of the initial temperature and the rapidity of 

 heating on the mode of decomposition of bodies, and especially 

 the seven different modes of the decomposition (some endo- 

 thermal, others exothermal) of ammonium nitrate, a definite 

 compound, which leads to more decisive conclusions than simple 

 mixtures. 



4. The following are the seven different modes of decomposi- 

 tion which ammonium nitrate undergoes. 



(a) The dissociation or partial decomposition of fused or even 

 gaseous ammonium nitrate into gaseous nitric acid and ammonia, 

 which seems to be first produced and at a low temperature. 

 It corresponds necessarily with absorption of heat, namely, 



