86 ANIMAL CHEMISTRY LECTURE IY. 



in the corrosive fluid of certain caterpillars, &c. Again, by 

 combining formic acid with ammonia, we obtain formiate of am- 

 monia, which yields by dehydration that important organic com- 

 pound met with in cherry-laurel water, bitter almond emulsion, 

 &c., and known as prussic acid, cyanide oi hydrogen, or formio- 

 nitrile, thus : 



Formic acid Ammonia Water Prussic acid 



CH,O a + H 3 N - aH,0 = CHN 



Moreover, this acid, or a corresponding cyanide, may nowadays 

 be procured, not only from formic acid, but by the direct com- 

 bination of carbon, nitrogen, and a metal. 



Further, by oxidising a cyanide that of potassium CKN, for 

 instance we obtain cyanate of potassium CKNO, convertible by 

 double decomposition into cyanate of ammonia, which changes 

 spontaneously into urea, thus : 



Ammonia cyanate Urea 



CHNO.H 3 N = CH 4 N a O 



This is the celebrated reaction by which urea was first produced 

 artificially by Wohler in 1828 ; but, at that time, the cyanogen 

 of the cyanide of potassium employed was known only as a 

 product of organic origin. You observe that by oxidising formic 

 acid CH 2 O 2 , we obtain carbonic acid ; and by oxidising the mon- 

 ammoniated form of formic acid namely, prussic acid CHN, in 

 presence of more ammonia, we obtain the di-ammoniated form 

 of carbonic acid namely, urea ; which has since been produced 

 by several other artificial processes. > 



(90.) The still less oxidised monocarbon compounds belong to 

 the methyl sub-group, and are, principally 



Methyl Compounds 



( CH 4 or CH 3 .H Methyl-hydride or marsh-gas 



|CH 5 C1 or CH 5 .C1 Methyl-chloride 



CH 4 or CH 3 .HO Methyl-hydrate or wood-spirit 



CH 5 N or CH 3 .H 8 N Methyl-amine 



