Ti 



Nitv Jmmal Acid, er the Zoonlc Acid. 367 



XII. 



Jtiformatlon refpeBhi^ the Zoonic Acid, difcovered by BeRTHOLLET, 



H E fluid * obtained by diftillation from animal fubftances has been hitherto thought 

 to contain no other principle than carbonate of ammoniac and an oil. Berthollet has af- 

 certained that it contains an acid, to which he has given the name of zoonic acid. He 

 has afcertained its prefence in the fluid obtained from the gluten of wheat, the yeaft of 

 beer, bones, and woollen rags, diftilled for the preparation of the muriate of ammoniac} 

 and be thinks himfelf authorized to confider it as the product of diftillation of all animal 

 fubftances. 



In order to feparate this acid, he mixes lime with the fluid afforded by this deflru£llvc 

 difiillation, after having feparated the oil. The mixture is then boiled or diftilled, to 

 feparate the carbonate- of ammoniac. When the odour ceafes to be penetrating, he filters 

 and adds a fmall quantity of lime to the liquid, which he again boils till the odour of am- 

 hioniac has entirely difappeared. What remains is the zoonate of lime, which he again 

 filters. To this he then adds the aqueous folution of carbonic acid, or otherwife he blows 

 through a tube into the liquor, in order to precipitate any lime which might exift in 

 the uncombined ftate. The zoonate of lime may then be ufed to produce other com- 

 pounds by double afHnity ; or the pure zoonic acid may be had by the following procefs : 

 The well concentrated aqueous folution of zoonate of lime is to be mixed with phof- 

 phoric acid, in a tubulated retort, and expofed to diftillation. The zoonic acid is not 

 very volatile, but requires a degree of heat nearly equal to that of boiling water to raife 

 •it. The fluid muft therefore be boiled ; and if two fucceffive receivers be at the fame 

 tirrie adapted, it will not be driven into the fecond. Part of the acid feems to be deftroyed 

 by the a£l:ion of the heat ; for the liquor becomes brown by the ebullition, and towards 

 the end of the procefs black : whence it may be concluded that this acid contains carbone, 

 Berthollet did not examine the other principles which are difengaged during the decom- 

 pofition. 



The zoonic acid has a fmell refembling meat which has been roafted ; a procefs in which 

 it is indeed formed. Its tafte is auftere, and, from the few experiments of Berthollet, no 

 remarkable properties were exhibited. It ftrongly reddens paper tinged with turnfol, and 

 effervcfces with alkaline carbonates. It did not appear to him to afford cryftallizable falts 

 with earths or alkaline bafes. It afforded a white precipitate in the aqueous folution of^ 

 acetite of mercury, and in that of nitrate of lead ; fo that it has a flronger attradion to 

 the.oxydes of mercury and lead refpeftively than the acetous and nitric acids. It docs 

 not a£t on the nitrate of filverbut by double affinity. The precipitate which then falls 

 down becomes brown in time, and therefore contains hydrogen. The zoonate of potafh 

 calcined did not' afford prufllate of iron with a folution of that metal. A liquid, pof- 

 fefllng all the characters of acidity, was feparated from flefli, which Berthollet had kept a 

 long time in a ftate of putrefaftion ; but it was an ammoniacal fait with excefs of acid. 

 This acid, combined with lime, appeared to him to refemble the zoonate of lime ; 

 but the quantity he had was too fmall to admit of its identity with the zoonic acid being 

 accurately determined. 



• Nearly in the words of Berthollet, in the Annales de Chimie, xwi. 86. 



3 B 2 XIII, HiHi- 



