ON MARKING INKS. 
163 
It appears to be difficult to state what is/properly speaking, 
" fulminating silver ;" but there can be no doubt that many 
of the combinations of that metal are highly dangerous, and 
should be used with the greatest caution. The fulminating 
silver of Brugnatelli and Howard, as also that of Liebig, is a 
cyanat^bf silver — the cyanogen, for the production of the 
cyanic acid, being derived from the carbon of the alcohol 
employed, and the nitrogen of the nitric acid ; but the fulmi- 
nating silver of Berthollet is a different substance altogether; 
no alcohol is used in its preparation, and nothing from which 
the carbon, for the production of cyanogen, could be derived, 
because Berthollet lays particular stress upon the necessity of 
employing ammonia which is quite free from carbonic acid. 
The detonating substance from the chloride of silver differs 
again, and contains neither oxygen nor carbon. We have 
here then three detonating compounds from silver, one con- 
taining Silver, Oxygen, Carbon, and Nitrogen; another, Silver, 
Oxygen, Hydrogen, and Nitrogen ; and one of Silver, Chlo- 
rine, Hydrogen, and Nitrogen. 
Probably, there are several other fulminating salts of silver 
differently constituted. Thomson states, that * fulminating 
silver was discovered by Berthollet in 17S8. It may be 
formed by dissolving very pure silver in nitric acid, and 
then precipitating it by lime water; the precipitate is put 
upon filtering paper, which absorbs the water and the nitrate 
of lime with which it was mixed, then pure liquid ammonia 
is poured upon it, and allowed to remain for twelve hours ; 
it is then decanted off, and the black powder, on which it 
stood, is placed cautiously, and in very small portions, upon 
bits of filtering paper. This powder is fulminating silver. 
Even while moist it explodes with violence when struck by a 
hard body ; when dry, the slightest touch is sufficient to cause 
it to fulminate. When the liquor decanted off this powder is 
heated in a glass retort, an effervescence takes place, azotic 
gas is emitted, and small crystals make their appearance, 
VOL. VIII. NO. II. 
21 
