Physics and Chemistry. 147 
certain direction, sa so the judgment is sophisticated.— Phil. 
ae A November, 
4. Kaplosion ie Can ‘bonic Acid in a coal mine.—M. teen 
has given in the Comptes Rendus a short state ment in 
an explosion in the coal mine of Rochebelle “Gard), wheal caused 
the death of three miners. is explosion is explained as having 
been produced, not b fire-damp, for the detonation was not accom- 
of i iron pyrites, tT his pyrite is stron ie oxidized and in a pe beeaise 
state of decomposition; this w give a continual source of sul- 
phurie acid, which, dissolving ‘little by little in the ni dsee 
waters, would meet the limestone below. In co nsequence a large 
amount of carbonic acid would be disengaged, penetrating the 
fissured beds of coal and: finally, as the author ro St accumulat- 
' Ing under so great a pressure as to lead to an explosio 
5. On the Heat of Formation of Cyanogen. raf vce cyanogen 
is the only electro-negative compound radical thus far isolated, 
BrrtHetor has thought it desirable to determine the heat of its 
formation. For this ] purpose he burned it by means of oxygen, 
and found for the heat of its combustion CN=26 grams =+132°3 
calories. Now the heat of combustion of the 12 grams of carbon 
it contains, referred to the condition of the diamond, is 94 ca lories. 
firm 
dioxide N,O,, cyanogen snot heat in its synthesis. This, Ber- 
thelot thinks, may be the reason why this body manifests in com- 
. Soe. 
One an energy sien to ee of the elements.—. 
Ch., I, xxxii, 385, Nov., 1879. 
6. First Book in Qualitative Ciinthies, by ALF ES- 
o. New York, (D. Van Nostrand) —This 
little work has a character of its own in that it is designed not 
otes on Assaying pe Assay Schemes; by P. DE ae 
TER Ricketts Second edition, revised and e 
larged. 2 vo, New York, 1879. (J. Wile Son Neck 
We noticed this useful volume on its first appearance. The second 
‘sora oe important additions and corrections hand- 
ers happy con eo = = Assay Ton a8 Pap vy which the 
ton of 2000 Ibs. stands A. T. as one ounce ae to one ore! 
