VOL. XC.J PHILOSOPHICAL TRANSACTIONS. 655 



this acid, on the application of heat, soon dissolved the powder, and extricated a 

 quantity of gas, which was found, by well known tests, to be nitrous gas mixed 

 with carbonic acid gas. The distillation was carried on till gas no longer came 

 over. The liquor of the retort was then mixed with the liquor collected in the 

 receiver, and the whole saturated with pot-ash ; which precipitated the mercury in 

 a yellowish-brown powder, nearly as it would have done from a solution of nitrate 

 of mercury. This precipitate was separated by a filter, and the filtrated liquor 

 evaporated to a dry salt, which was washed with alcohol. A portion of the salt 

 being refused by this menstruum, it was separated by filtration, and recognized by 

 all its properties, to be nitrate of pot-ash. The alcoholic liquor was likewise eva- 

 porated to a dry salt, which, on the affusion of a little concentrate sulphuric acid, 

 emitted acetous acid, contaminated with a feeble smell of nitrous acid, owing to 

 the solubility of a small portion of the nitre in the alcohol. 



§ 12. The sulphuric acid acts on the powder in a remarkable manner, as already 

 has been noticed. A very concentrate acid produces an explosion nearly at the 

 instant of contact, on account, I presume, of the sudden and copious disengage- 

 ment of caloric from a portion of the powder which is decomposed by the acid. 

 An acid somewhat less concentrate likewise extricates a considerable quantity of 

 caloric, with a good deal of gas ; but, as it effects a complete decomposition, it 

 causes no explosion. An acid diluted with an equal quantity of water, by the aid 

 of a little heat, separates the gas so much less rapidly, that it may with safety be 

 collected in a pneumatic apparatus. But, whatever be the density of the acid, 

 provided no explosion be produced, there remains in the sulphuric liquor, after the 

 separation of the gas, a white uninflammable and uncrystallized powder, mixed 

 with some minute globules of quicksilver. 



To estimate the quantity, and observe the nature, of this uninflammable sub- 

 stance, I treated 100 gr. of the fulminating mercury with sulphuric acid a little 

 diluted. The gas being separated, I decanted off the liquor as it became clear, 

 and freed the insoluble powder from acid, by edulcoration with distilled water; 

 after which I dried it, and found it weighed only 84 gr.; consequently had lost 

 16 gr. of its original weight. Suspecting, from the operation of the nitric acid in 

 the former experiment, that these 84 gr., with the exception of the quicksilver 

 globules, were oxalate of mercury, I digested them in nitrate of lime, and found 

 my suspicion just. The mercury of the oxalate united to the nitric acid, and the 

 oxalic acid to the lime. A new insoluble compound was formed; it weighed, when 

 washed and dry, 48.5 gr. Carbonate of pot-ash, separated the lime, and formed 

 oxalate of pot-ash, capable of precipitating lime-water, and muriate of lime; though 

 it had been depurated from excess of alkali, and from carbonic acid, by a previous 

 addition of acetous acid. That the mercury of the oxalate in the 84 gr., had united 

 to the nitric acid of the nitrate of lime, was proved by dropping muriatic acid into 

 the liquor from which the substance demonstrated to be oxalate of lime had been 

 separated; for a copious precipitation of calomel instantly ensued. 



