116 Researches on the Constitution of the Fatty Substances, hy 



The oleic acid, when treated with nitric acid, produces also 

 margaric and suberic acid. The mother hquor from which 

 these have separated contain the pimelic and adipic acids dis- 

 covered by Laurent. For the first, M. Bromeis verified 

 Laurent's formula, C^ H^ Og + Aq, but for the second he ob- 

 tained a different result, viz. C14 Hg 0^ + 2 Aq. 



Laurent had supposed that oenanthic acid was produced 

 in this process, but Bromeis could not obtain any satisfactory 

 evidence of its formation, nor has he as yet been able to verify 

 the history of the lipic and azoleic acids as given by that che- 

 mist. 



The drying oleic acid from linseed oil gave with nitric acid 

 neither pimelic acid nor adipic acid, but a large quantity of 

 oxalic acid, of which the proper oleic acid yields none. 



It has been long known that when olive oil is mixed with 

 a solution of proto-nitrate of mercury it becomes solid, and 

 this property, which was once made use of to determine 

 the purity of olive oil, has been found to belong to almost 

 all fatty bodies in a greater or less degree. Boudet proved 

 that the action of the mercurial solution depended exclusively 

 on the hyponitrous acid in the liquor, and that the same ef- 

 fect was produced by hyponitrous or nitrous acid fumes alone. 

 He also pointed out that the solid mass produced was a com- 

 pound of glycerine with a peculiar acid, which he termed 

 the elaidic, as he gave the name of elaidine to this artificial 

 fat. 



The only numerical results obtained of the constitution 

 of this acid were given by Laurent. From his analyses the 

 formula for the crystallized elaidic acid should be C35 H33 O3 

 + Aq, and for the elaidic ^ther the formula C35 H33 O3 



From this constitution, however, no insight into its origin 

 could be obtained, and Maj'er undertook in Liebig's labo- 

 ratory the complete revision of its history. 



M. Mayer found the modes of preparation prescribed and 

 followed by Boudet and by Laurent quite insufficient to ob- 

 tain a product of absolute purity. He arrived ultimately at 

 the result that it is onl^^ from the oleic acid that the elaidic 

 acid is produced, and hence to form it he had recourse lo 

 absolutely pure oleic acid prepared by the method of Varren- 

 trapp, which will be described by and by. It may also be pre- 

 pared nearly, but not so absolutely pure, by passing a stream 

 of nitrous acid vapour through oil of sweet almonds. Nitric 

 oxide gas passes off^ and the oil, when exposed to cold, gives 

 a copious crop of crystals of elaidic acid. 



Elaidic acid is of a brilliant white colour, crystallizes in 



