316 Intelligence and Miscellaneous Articles. 



tion of an alkaline silicate or from fluoride of silicium, is a hydrate 

 of definite proportions, the composition of which may be represented 

 by the formula HO. Si O?. This hydrate, when heated to 212° F., 

 loses one equivalent of water, and is converted into another com- 

 pound, HO, 2Si 03. 



6. That when a solution of an alkaline silicate is treated with a 

 metallic solution, a precipitate is formed, which is a mixture of hy- 

 drate of silica and a metallic silicate ; the metallic silicate being 

 entirely dissolved by the mineral acids, while the free silica re- 

 mains undissolved. 



7. That a limpid and very strong solution of silica in hydrochloric 

 acid may be obtained by dissolving in this acid silicate of copper, 

 and precipitating the copper by sulphuretted hydrogen. 



8. That a solution of silica in hydrochloric acid, slowly evaporated 

 under the receiver of the air-pump, gives hydrate of silica (HO, Si O^) 

 perfectly crystallized in very small transparent needles, grouped 

 either in stars or tufts. — Comptes Rendus, Juillet 19, IS^?. 



ON NITRIC MANNITE. BY M. SOBRERO. 



Since the action of nitric acid on organic bodies has been 

 studied, a number of substances of great interest to science have 

 been discovered ; but the arts have hitherto acquired only fulraina- 

 ting-cotton, the fate of which is as yet uncertain. Whilst the ques- 

 tion as to cotton is under consideration, M. Sobrero announces to 

 the Academy another body which is fulminating in the highest de- 

 gree, resulting from the action of nitric acid upon mannite — the 

 nitric mannite, the composition of which has been already given by 

 MM. Flores Domonte and Menard. 



Fulminating mannite possesses the property of detonating by the 

 stroke of a hammer with as much violence as fulminate of mer- 

 cury, and produces, during its decomposition, sufficient heat to in- 

 flame gunpowder. As soon as the author was acquainted with this 

 property, he set about to apply it, and prepared capsules with it 

 instead of detonating mercury for the discharge of fire-arms, and a 

 fowling-piece was discharged by it. 



With respect to its use, the author has arrived at the following 

 conclusions : — 



1 . Fulminating mannite must always be cheaper than fulminating 

 mercury. 



2. It is more conveniently prepared, and does not expose the 

 workmen to the great danger which attends the manufacture of 

 fulminating mercury. 



It must be cheaper than fulminating mercury, because the price 

 of manna is not very high ; because in the preparation of mannite 

 an uncrystallizable residue is obtained, mixed with a little mannite, 

 which may be employed in medicine and the veterinary art as a 

 purgative ; and because, according to the analyses of MM. Flores 



