328 
Journal of Agricultural Research 
Vol. XXVI, No. 8 
were not obtained, a method described by Nicolet and Jurist (26) was 
employed. No difficulty was experienced in obtaining a fairly pure 
product, in the form of pale, greenish-yellow crystals that melted at 
84.9° to 85.3° C., as compared with 86° C., reported in the literature for 
the pure product. 
As already observed, diketostearic acid was found to be odorless. 
Furthermore, neither the acid itself nor a nonrancid lard to which it had 
been added responded to the Kreis test. 
Azelaic acid. —Azelaic acid has been recovered from rancid fats (27) 
and has been obtained as a cleavage product of oleic acid ozonid (38). 
While a certain amount of this product was obtained from oleic acid 
ozonid in the course of these studies, a larger quantity was obtained as a 
by-product from the preparation of dihydroxystearic acid. 
The acid solution from which the dihydroxystearic acid had been 
precipitated was concentrated to a small volume and allowed to cool. 
A mass of white crystals separated, as well as a small amount of oily sub¬ 
stance, which floated, for the most part, on the surface of the liquid. 
The oil was removed mechanically so far as possible, after which the 
crystals were collected on a filter and repeatedly recrystallized from hot 
water. 
A white, well-crystallized product was obtained which melted at 99.1 0 
C. as compared with 106° C. for pure azelaic acid. The low melting point 
was presumably due to the incomplete separation of the oily substance, 
presumably pelargonic acid. The product was odorless, and failed to 
react in the Kreis test, either alone or in presence of nonrancid lard. 
Pelargonic acid. —Pelargonic acid has been isolated from rancid 
fats by Scala (37) and has been obtained as a cleavage product of oleic 
acid ozonid and as one of the products in the oxidation of oleic acid with 
potassium permanganate. 
A sample of this acid boiling at 252 0 to 255 0 C, as compared with 
252 0 to 254 0 C. for the pure product, was obtained through the courtesy 
of Doctor Spencer of the Bureau of Chemistry of this department. It 
was found to have a mild odor, and in small quantities was without 
appreciable effect on the odor of a nonrancid lard to which it had been 
added. Negative Kreis tests were obtained both on the substance 
itself and on the lard containing it. 
Caprylic acid. —Caprylic acid has been isolated from rancid fats by 
Scala (37), who was of the opinion, however, that it had nothing to do 
with the odor of rancidity. 
A sample of this compound obtained by purchase was found to boil 
from 237.2 0 to 238.5° C., as compared with the reported boiling point of 
from 236° to 237° C. for the pure substance, and was probably a fairly 
pure product. Its odor was similar to, but stronger than, that of pelar¬ 
gonic acid, and somewhat suggestive of cocoanut. When added to 
sweet lard in the amount of 1 per cent it imparted to the lard an odor 
weaker than that of a rancid control and of a different type. While 
its presence in rancid fats is not questioned, it would appear that it 
has nothing to do with the rancid odor. Negative Kreis tests were 
obtained both with caprylic acid itself and with the lard to which it 
had been added. 
Heptylic acid. —Heptylic acid has been isolated from a rancid fat 
by Scala (57). A purchased sample distilled for the most part between 
221.3 0 and 222.3 0 C., as compared with 223° to 223.5 0 C. for the pure 
acid. In the amount of 1 per cent it imparted to a nonrancid lard the 
