1824.] Fulminate of Silver. 425 



hydrocyanic acid. A portion of it must, therefore, remain in the 

 new acid, and 7 proportions of chloride of silver are obtained : 

 it is evident, therefore, that a part of the chlorine is combined 

 with hydrogen in the new acid. 



For the purpose of obtaining some information in this respect, 

 we attempted to ascertain the quantity of hydrocyanic acid 

 which is evolved when fulminate of silver is treated with muriatic 

 acid. 



A known weight of fulminate of silver was put into a three- 

 necked bottle, fig. 6, with water placed in a salt-water bath, and 

 afterwards muriatic acid was poured through the tube, f, upon 

 the fulminate. In order to facilitate the volatilization of the 

 hydrocyanic acid, a current of hydrogen gas was passed into the 

 fluid, from a bottle, a, containing a mixture of zinc and sulphuric 

 acid. The hydrogen gas passed through a tube, d, containing 

 fragments of marble with a little water, and afterwards escaped 

 through a solution of nitrate of silver contained in the receiver, e. 

 We were in hope of obtaining cyanuret of silver ; but to our 

 great surprise no precipitation took place, although we were 

 certain that the same solution of silver gave an abundant preci- 

 pitate when hydrocyanic acid was poured into it. 



Hydriodic acid acts upon fulminate of silver in the same way 

 as muriatic acid. Hydrocyanic acid is disengaged, and a pecu- 

 liar acid is formed which contains iodine, and possesses the pro- 

 perty of precipitating perchloride of iron immediately of a deep- 

 red colour. 



When a current of sulphuretted hydrogen gas is passed 

 through water containing suspended fulminate of silver, the 

 fulminate is also decomposed ; sulphuret of silver and a peculiar 

 acid are obtained, of which sulphur is one of the elements, but 

 no smell of hydrocyanic acid is perceptible. 



This new acid ha3 a sweetish taste ; it immediately colours 

 perchloride of iron of a deep-red colour; the solution may be 

 evaporated, and concentrated without decomposition. Com- 

 bined with potash and evaporated to dryness, it suffers no 

 alteration. 



22-68 of fulminate of silver, treated with sulphuretted hydro- 

 gen, produced sulphuret of silver, which, treated with nitric 

 acid, and afterwards with muriatic, gave 21*73 of chloride of 

 silver. 



The new acid, saturated with potash, evaporated and heated 

 to redness in a capsule of platina with nitre, saturated and pre- 

 cipitated by chloride of barium, produced 18-60 of sulphate of 

 barytes, representing 22-89 of chloride of silver. These two 

 quantities of chloride, not being very different, seem to admit of 

 the conclusion, that in fulminic acid, the sulphur exactly 

 replaces the oxygen atom for atom ; but a second experiment 

 indicated by sulphate of barytes a rather smaller proportion than 

 the first. 



