350 PROCEEDINGS OF THE AMERICAN ACADEMY 



" The fatty acids obtained from the various animal and vegetable 

 fats that occur in nature, it is known, are divided into two principal 

 classes. 



" The one class forms a part of the series of acids constituted ac- 

 cording to the formula C„ H„ O4, while the other class forms the series 

 with the formula C^ H„_2 O4. The former series is by far the more 

 completely developed, there failing but a few members, from formic 

 acid, Co H2 O4, up to arachinic acid, C40 H40 O4. As we pass from one 

 acid to another in this series, there is a gradual change in the prop- 

 erties of successive acids, corresponding to the change in the for- 

 mula, — a change which is exhibited more especially in the boiling 

 point of those acids which can be distilled undecomposed, or in the 

 melting points of those that cannot be. 



" The other series is much less extensive, only the following mem- 

 bers being yet known : — 



Brassinic acid C4S H43 O4 



Erucaic acid C44 H42 O4 



Dciglingic acid C38 Has O4 



Oleic acid C36 H34 O4 



Hypogaeic acid C32 H30 O4 



Moringaic acid C30 Hjs O4 

 " Also, in this series we observe none of that perfect correspond- 

 ence between the formulae and properties of different acids in rela- 

 tion to one another. 



" This latter series being at the present time rendered an object of 

 more special interest by the discovery of a new member, we give 

 here a short account of the series in general, in connection with the 

 result of investigations on this new member, which its discoverer. Dr. 

 A. Goessmann, afforded us an opportunity of making, in the labora- 

 tory of Professor Wohler in Gottingen. 



••' The oleic acid, the principal and best-known member of this 

 series, was discovered by Chevreul, and its characters were subse- 

 quently completely developed by Gottlcib. It is a solid fat at low 

 temperatures, but melts at 16° C, and then oxidizes very readily in 

 the air, thereby becoming changed to a reddish-yellow oil. Two 

 very characteristic properties of this acid are as follows : — 



" First. Under the influence of nitrous acid gas, it is transformed 

 into an isomeric modification, not oxidizable in the air, and possessing 

 a higher melting point than the oleic acid itself 



