Eobertson. — Fatty Acids and their Esters, dc. 579 



Some closely connected law seems to regulate the distri- 

 bution of the fatty acids in nature. A rough analysis of the 

 fatty acids obtained by the saponification of cocoa-butter 

 showed that the compounds were present in the following 

 proportions : — 



Butyric acid (C 4 ) 2 per cent. 



Hexoic acid (C 6 ) 

 Octoic acid (C 8 ) 

 Decoic acid (C 10 ) 

 Laurie acid (C 12 ) 







1 



4 



50 



Here again it is the sixth member which occurs to the smallest 

 extent. 



ffr Though smell is a property concerning which little is 

 known, yet it does not seem entirely devoid of interest to 

 mention that of all the even fatty acids hexoic acid has the 

 most repugnant odour. Thus it seems as if, in the case of 

 the cocoa-tree, the most offensive acid is prepared in the least 

 quantity by the plant. 



A study of the cyoscopic behaviour of the normal fatty 

 esters in phenol solution gives somewhat similar results, in 

 that it is again at the sixth member that a sudden change is 

 exhibited. In the case of these compounds, however, there 

 is also a change of the opposite nature at the compound with 

 twelve atoms. This appears to be the first instance known 

 of the regular occurrence of both a maximum and minimum 

 in the same series of compounds. 



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