1824.] Fulminate of Silver. 421 



to prove that the formation of one of these compounds prevented 

 that of the other. Now, supposing that all the hydrogen com- 

 bined with the cyanogen in the fulminate of silver was combined 

 with the azote to form ammonia, a very appreciable quantity of 

 carbonate of ammonia ought to be obtained. 



Indeed the 5*32 grains of fulminate decomposed by oxide of 

 copper ought to yield 32*04 cubic inches of gas, composed of 

 two-thirds of carbonic acid and one-third of azote. And as 

 there is in hydrocyanic acid as much hydrogen in volume as of 



azote, 32-04 cubic inches represent — — = 10-68 of hydrogen 



gas, which, combined with their third of azote, ought to produce 



■ = 7-12 of ammoniacal gas : this quantity would 



absorb 3-56 of carbonic acid gas to form carbonate of ammonia, 

 and the total diminution which would result from the disappear- 

 ance of carbonic acid gas and that of azote, would be equal to 

 7'12 cubic inches. In our experiment, notwithstanding the 

 formation of nitrous acid, we obtained 29*64 cubic inches, the 

 difference between which and 32-04 is very far from being equal 

 to that which ought to be obtained, if all the supposed hydrogen 

 had been taken up to form ammonia. The hypothesis that a por- 

 tion would produce water cannot be admitted ; for, as we have 

 already remarked, when carbonate of ammonia is formed, not 

 the slightest trace of moisture is perceptible ; and further, we 

 have proved by direct experiment, that by moistening the ful- 

 minate of silver, much carbonate of ammonia is obtained. 



Thus the decomposition of fulminate of silver mixed with sul- 

 phate of potash furnishes us with additional proof that it does 

 not contain hydrogen as one of its elements. The fulminate of 

 silver in the preceding experiment having given two portions of 

 gas, one with sulphate of potash, and the other with oxide of 

 copper, it was important to ascertain the nature of each of them. 

 We made a fresh experiment directed solely to this end ; but 

 being desirous of obtaining the first portions evolved without 

 any admixture of atmospheric air, we endeavoured to form a 

 vacuum in our apparatus. 



To the tube containing the mixture, we adapted a copper tube, 

 <-, fig. 5, connected with a glass tube, d, nearly 40 inches long, 

 and immersed it in a basin of mercury, m, in order to collect the 

 gases. From the middle of the copper tube, another, c, projects 

 at a right angle, furnished with a cock, and communicating with 

 the air-pump by means of a leaden pipe, i. On making a vacuum 

 in the apparatus, the mercury cannot pass the height, h, equal 

 to about thirty inches, and by then turning the cock, all commu- 

 nication between the apparatus and the air-pump is shut off. 



In employing this apparatus, we found that the gas evolved 

 during the distillation of the fulminate of silver witli the sulphate 

 of potash, is composed of two volumes of carbonic acid gas and 



