654 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. 



begins to undulate on the surface of the liquor ; and the powder will be gradually 

 precipitated, on the cessation of action and re-action. The precipitation is to be 

 immediately collected on a filter, well washed with distilled water, and carefully 

 dried in a heat not much exceeding that of a water bath. The immediate edulco- 

 ration of the powder is material, because it is liable to the re-action of the nitric 

 acid ; and while any of that acid adheres to it, it is very subject to the influence 

 of light. Let it also be cautiously remembered, that the mercurial solution is to 

 be poured on the alcohol. 



I have recommended quicksilver to be used in preference to an oxide, because it 

 seems to answer equally, and is less expensive ; otherwise, not only the pure red 

 oxide, bui the red nitrous oxide and turpeth may be substituted ; neither does it 

 seem essential to attend to the precise specific gravity of the acid, or the alcohol. 

 The rectified spirit of wine and the nitrous acid of commerce, never failed to pro- 

 duce a fulminating mercury. It is indeed true, that the powder prepared without 

 attention, is produced in different quantities, varies in colour, and probably in 

 strength. From analogy, I am disposed to think the whitest is the strongest; for 

 it is well known, that black precipitates of mercury approach the nearest to the 

 metallic state. The variation in quantity is remarkable ; the smallest quantity I 

 ever obtained from 100 gr. of quicksilver being 120 gr, and the largest 132 gr. 

 Much depends on very minute circumstances. The greatest product seems to be 

 obtained, when a vessel is used which condenses and causes most ether to return 

 into the mother liquor ; besides which, care is to be had in applying the requisite 

 heat, that a speedy, and not a violent action be effected. 1 00 gr. of an oxide are 

 not so productive as 100 gr. of quicksilver. As to the colour, it seems to incline 

 to black, when the action of the acid on the alcohol is most violent, and vice versi. 



§ 10. I need not observe, that the gases which were generated during the com- 

 bustion of the powder in the glass globe, were necessarily mixed with atmospheric 

 air; the facility with which the electric fluid passes through a vacuum, made such 

 a mixture unavoidable. The cubical inch of gas received over water was not 

 readily absorbed by it : and as it soon extinguished a taper, without becoming red, 

 or being itself inflamed, barytes let up to the 3 cubical inches received over mer- 

 cury, when a carbonate of barytes was immediately precipitated. The residue of 

 several explosions, after the carbonic acid had been separated, was found, by the 

 test of nitrous gas, to contain nitrogen or azotic gas; which does not proceed 

 from any decomposition of atmospheric air, because the powder may be made to 

 explode under the exhausted receiver of an air-pump. It is therefore manifest that 

 the gases, generated during the combustion of the fulminating mercury, consist 

 of carbonic acid and nitrogen gases. 



$11. The principal re-agents which decompose the mercurial powder, are the 

 nitric, the sulphuric, and the muriatic acids. The nitric changes the whole into 

 nitrous gas, carbonic acid gas, acetous acid, and nitrate of mercury. I resolved 

 it into these different principles, by distilling it pneumatically with nitric acid : 



