426 A nalysis of Fulminate of Silver. [J u N e, 



Fluojric-acid does not act upon the fulminate of silver; the 

 cause of this is not to be found in the solubility of fluoride of 

 silver, for fulminate of copper is perfectly decomposed by muria- 

 tic acid. This fact appears to us important in the hitherto 

 somewhat problematical history of fluoric acid. 



The three peculiar ac:ds of which we have spoken as colouring 

 the perchloride of iron of a deep-red colour, must possess a 

 common principle as the cause of this property. It is worthy of 

 remark, that the slightly fulminating timet, several properties of 

 which have been detailed by M. Chevreul, and the sulpho-cyanic 

 acid of M. Porret, give the same red colour to perchloride of 

 iron. 



Oxalic acid decomposes fulminate of copper and of silver ; 

 hydrocyanic acid and ammonia are produced ; no effervescence 

 is perceptible, which seems to prove that no carbonic acid is 

 formed. Sulphuric acid gives similar results. 



We may remark, with respect to the preparation of the alkaline 

 fulminates, that fulminic acid having the property of forming 

 very variable double salts, it is preferable in obtaining the 

 double fulminate of silver and potash, for example, to decompose 

 the fulminate of silver by chloride of potassium. It may be 

 immediately obtained in a state of purity, by employing only 

 exactly the quantity of chloride sufficient to precipitate half 

 the silver combined with the fulminic acid, or rather a little 

 less, since the fulminate of silver which is undecomposed, 

 being but little soluble, would remain with the chloride of silver. 

 Nevertheless the limit of the total decomposition of the fulmi- 

 nate of silver may easily be ascertained by using heat, because 

 the fulminate being then slightly soluble, aprecipitateis obtained, 

 if any remain undecomposed, by adding a little of the chloride. 

 We repeat that all the fulminates, single or double, detonate 

 with great facility, even in water, and that glass stirrers should 

 not be used to agitate any fluid, which contains them in a state 

 of mixture. We accidentally detonated, by this method, fulmi- 

 nate of silver and barytes in a porcelain capsule ; the accident 

 fortunately produced no ill effects, because the greater part of 

 the fulminate was suspended in the liquid, and it was scarcely 

 warm ; but without this union of circumstances, the conse- 

 quences would have been terrible. 



