144 Scientific Intelligence. 
mental deduction from his thermochemical researches, BERTHELOT 
proved long ago the tendency of chemical systems toward that 
composition which corresponds to the maximum evolution of heat. 
He now notes an excellent illustration of this law in the case of 
barium perhydrate, which decomposes spontaneously, while 
barium peroxide is permanent. A specimen of BaO, prepared 
in 1874 contained 9:4 oxygen in excess, and in 1877, 9°2 of this 
oxygen; showing its permanence. The hydrate however, BaO, 
(H,O),, prepared pure and kept moist, gradually decomposes, 
gas bubbles of oxygen developing in the mass, generating a pres- 
sure in the vessel, and forming a crystalline mass o 
hydrate BaO, (H,O),,. This decomposition is even more rapid 
under water. A specimen prepared in 1874 and kept moist, had 
spontaneous decomposition of barium perhydrate is not to be 
found in any symbolic considerations, drawn from a figurative 
arrangement of atoms; but is explained by very simple and very 
obvious principles, resulting from the regular action of molecular 
mechanics,”— Bull. Soc. Ch., I, xxviii, 502, Dec. 1877. G. F. B. 
6. On the Hydrocarbon called Idryl.—Gotpscumiept has sub- 
ul was the alcoholic extract of the chamber deposit, and fused 
from 75° to 86°. By solution in alcohol, difficultly soluble flocks 
were observed which were filtered off and marked A. They fused 
at about 200°. From the filtrate, or from the more fusible por- 
dissolved in aleohol and mixed with a 
solution of picric acid. Red crystalline precipitates were thus 
nt. On concentration, additional picrate was obtained but 
ighter in color as it was more soluble. The portions having 
