PROJECTILES CON-TAINING EXPLOSIVES A. R. 141 



of those bodies that are utilized to-day, which are picric acid, tri- 

 nitrocresol, trinitrotoluene, trinitronaphthalene, and the mixture of 

 ammonium nitrate and dinitronaphthalene known as Favier's explo- 

 ive. There will be added also some bodies of the same series which 

 appear susceptible of use, but of which we have no example. 



1.. Picric acid. — Picric acid or trinitrophenol (melinite, lyddite, 

 schimose) occurs in small yellow crystals which possess a strong 

 coloring power. It is but slightly soluble in water at ordinary tem- 

 perature, but this solubility increases as the temperature is raised. 

 It is readily soluble in acetone. Melinite is fused at about 122° C. 

 Its reactions are acid and it forms with metals (save tin) crystalline 

 salts of marked color. Speaking generally the picrates are markedly 

 explosive and they are the more unstable the heavier the metal which 

 enters into their constitution. Lead picrate is especially dangerous. 

 Iron picrate is much less so and its explosion in use can not occur 

 if the explosive is moist. In order to prevent its formation the walls 

 of the projectiles are so varnished or coated with plating as to pre- 

 vent their direct contact with the explosive. 



It follows that because of the dangerous character of the lead 

 picrate the tin used with which to coat the walls of the shell should 

 be extremely pure. The care to be taken in avoiding, in the course 

 of charging, the production of picrates is of the first importance and 

 it is not to be overlooked as a factor in deciding against picric acid 

 in comparison with those which follow it. 



Picric acid may be detonated in several ways. That detonation of 

 it which is called " complete " is characterized by the production of 

 dense black fumes holding free carbon in suspension in them. In 

 the detonation styled "incomplete" the explosion gases have a 

 greenish-yellow color and at the same time they deposit a layer of 

 undecomposed explosive on the surrounding objects. The energy 

 set free in the complete is greater than in the incomplete detonation. 



The reactions attending these two methods of detonation are 

 approximately as follows : 



Complete detonation 2C6H2(N02)30H-^8CO+3C02+3H2-f SNa-f-C. 

 Incoi}iplete detonation 2C6H2(N02)30H-^llC04-C02-l-H20-}-2H2+3N2. 



It is evident that in the case of a reaction effected by detonation 

 in an extremely resistant envelope the consideration of the products 

 will, in virtue of the displacement of the equilibrium, give prin- 

 cipally those shown in the first equation. 



Admitting there is obtained under an infinite pressure the maxi- 

 mum condensalion represented b}^ the equation 



4CoH2(N02)30H-»14C02-f3CH4-F7C 



