'SSi Essay vpon the Compounds of Cyanogen. 



5. That it is a compound of ferrocyanic acid and peroxide of 

 iron, and like all other salts of the same base, contains 1.5 atoms of 

 acid + 1 atom of base — and 



6. That the following is the only constitution which can be recon- 

 ciled with the above facts : 



Atoms. Atoms. 



3 cyanogen, 78 

 1.5 ferrocyanic acid <( 1.5 iron, 42 



lr5 hydrogen, 1.5 



, .J r ' O iron, 



I peroxide ot ircwi < ^ c 

 ^ (1.5 oxy£ 



28 

 oxygen, 12 



1 water l\ ^F"' ? 



1 hydrogen, 1 



170.5 representative number. 



Argento-cyanic acid* — This name I take the liberty of proposing 

 for the peculiar acid which M. Just Liebig first separated from How- 

 ard's fulminating silver, and which he described in the Ann. de 

 ChimiGj Sec. under the name of ' fulminic acid.' In a subsequent 

 essay, which was the joint production of Liebig and Gay-Lussac, a 

 number of experiments are recorded, which tend to elucidate its ul- 

 timate constitution, but do not seem to me capable of justifying the 

 inference that has been drawn from them, that the compound is a 

 supercyanite* of silver. When lime water is poured upon the fulmi- 

 nating compoimd, decomposiUon ensues, and oxide of silver is sepa- 

 rated. "When this has perfectly subsided, the liquid is to be decant- 

 ed, and on the addition of nitric acid, a white precipitate falls, which 

 Is the f)ilminic or argenio-cyanic acid. In this process we may sub- 

 stitute for lime water, any of the other alkalies or earths, with the ex- 

 ception of ammonia, which holds the oxide of silver in solution, and 

 gradually gives rise to another well know^n detonating compound 

 that discovered by Berthollet, 



The argento-cyanic acid is a white powder, slightly soluble in cold, 

 but more so in boiling water, and from either solution it may be ob- 

 tained in crystals. It reddens litmus, and is capable, as we have al- 

 ready seen, of combining with and neutralizing bases. With pot- 

 assa and soda it forms crystalline salts, of a disagreeable metallic 





*In the essay alluded to, which appeared before Serullas had announced the dis- 

 covery of the cyanic acid, the compound was called ^supercyanate of silver. 



