ON THE SEBACIC AflD. 



3T 



P. Examination of the ProceJJes that have hitherto been employed 



for obtaining Sebacic Acid. 



CRELL, in order to feparate the febacic acid from the pro- Crell's procefs 



duct of diftilled fat, firft added to it a certain quantity of pot- f 7t with pot "ih, 



afh, after which he filtrated and evaporated it. As the fait filtration, cva- 



which he obtained was mixed with oil, he calcined it, after P oration > « lci - 



. nation, and rc- 



whichhe re-diflblved it in water, and evaporated the folution. foiutkmof the 

 By this means he obtained a fait of confiderable whitenefs, and fal *i ; and la .'y 



/ r i- i , . , . , i •• vi diftillanon with 



of a foliated texture,; this he introduced into a retort, with f u i p huric acid, 

 fulphuric acid, and diftilled it, whereby he obtained a pungent 

 and fuming acid. But as this procefs appeared to him to be 

 an inconvenient one, he had recourfe to the following : 



Perfuaded that the acid of fat exifted ready formed in the Another by 

 fat itfelf, and was not a product of diftillation, he prepared a t °g™|j|f Si** 

 foap with fat and potafti, and treated this foap with water, in water, and fome 

 order to diflblve the febate of potafli formed in it. But as the J^j^jJ 1 

 water, befides the febate of potafli, diflblved alfo a certain 

 quantity of fat combined with potalh, he added to the folution 

 of this febate of potafli and of this foap, a fufficient quantity of 

 alum. By this means he obtained febate of potafli, which 

 had only an admixture of fulphate of potafli ; this he evapo- 

 rated, poured fulphuric acid upon the dry fubftance, applied 

 heat ; and febacic acid patTed into the receiver. 



- In the chemiftry of Dijon, we find a procefs different from Dijon procefs. 



that of Crell. According to this procefs, the fat is calcined Calcination of 



with a certain quantity of lime, in a crucible ; the fubftance (? . w .'* hme » 



n , J , ■ hxiviation, eva- 



is then lixiviated with a large quantity of water ; the water poration, and 

 which holds the calcareous febate in folution, is evaporated ; diftillation with 

 this calcareous febate is introduced into a retort with fulphuric 

 acid, and the febacic acid pafles into the receiver. 



- Thefe three procelTes I have repeated with the utmoft care, Crell's firft pro, 

 and have obtained the following remits. The firft of CrelPs ^^^ 

 ■procefles, and that of the chemiftry of Dijon, afforded me an 



acid which has all the characterises of the acetous acid: with 

 •potafh it forms a foliated fait, which- is deliquefcent, has an 

 extremely pungent tafte, and on, being treated with fulphuric 

 acid, yields a large quantity of vinegar. If Crell, as he af- 

 ferts, has obtained a fuming and pungent acid, I prefume that . i • • 

 it is a fmall quantity of fulphurcpus acid, proceeding from the 



decompofition 



