350 
Journal of Agricultural Research 
Vol. XXVI, No. 8 
contact with concentrated hydrochloric acid into a substance more 
soluble in water, or at least in concentrated hydrochloric acid, which is 
probably identical with substance K. 
Vacuum distillation of rancid oleic acid (i). —A considerable 
quantity of U. S. P. oleic acid was aerated in a series of Folin cylinders 
in a light window from June 12 to July 26, at the end of which time 
it was intensely rancid as evidenced by its odor and its strong response 
to the Kreis test. 
One hundred cc. of this material was subjected to fractional distilla¬ 
tion at a pressure varying from 0.3 to 2 mm. Identical amounts of the 
several fractions were used in the tests described. 
Fraction 1 .—Distilled under 40° C. This fraction consisted of a cloud which could 
not be condensed. 
Fraction 2. —Distilled up to 120° C., but principally between 8o° and no 0 C. 
This fraction consisted of 2 to 3 cc. of a pale yellow oil having a slightly scorched and 
slightly pungent odor. The aldehyde test with Schiff’s reagent gave a strong indigo 
color. The peroxid test with potassium iodid was strongly positive. The Kreis 
test gave a distinct, though not an intense, red color together with a cream-colored 
precipitate at the interface between the two layers. 
Fraction 3. —Distilled between 120° and 155 0 C. This fraction was somewhat 
larger in quantity than Fraction 2, which it resembled in odor and appearance. In 
the Schiff test a strong purple color was obtained. In the Kreis test it reacted like 
Fraction 2, but somewhat more weakly. A weak test forperoxids was obtained. 
* Fraction 4 .—Distilled between 155 0 and 175 0 C. In physical character this frac¬ 
tion resembled Fractions 2 and 3. Its response to the aldehyde test was weaker 
than that of the lower fractions, while the Kreis test and the peroxid test were prac¬ 
tically negative. 
Fraction 5.—Distilled from 175 0 to 180° C. (2-mm. pressure). This fraction con¬ 
sisted of a pale-yellow oil of blana odor. It gave a faint test for aldehydes, a negative 
peroxid test, and a negative Kreis test. 
Fraction 6. —Distilled up to 185° C. (0.5-mm. pressure). The bulk of the distillate 
was contained in this fraction, which resembled Fraction 5 in appearance and odor. 
The Schiff test, the peroxid test, and the Kreis test were all negative. 
Fraction 7.—Distilled between 185° and 188 0 C. About 8 to 10 cc. of distillate 
were obtained in this fraction, which resembled Fractions 5 and 6 as to its appearance 
and odor and as to the negative results obtained in the three tests. 
Residue. —The residue in the distilling flask was a thick, viscous liquid of a dark, 
reddish-brown color. It appeared to give negative results in the Schiff test, the 
peroxid test, and the Kreis test, although in the latter test a weak reaction might 
have been obscured by the color that the liquid imparted to the hydrochloric acid. 
In the foregoing experiment none of the fractions responded to the 
Kreis test as strongly as the original sample before distillation, and a 
loss of Substance R is indicated. Since of the fractions collected, 
Fraction 2 seemed to respond most strongly, the possibility was sug¬ 
gested that even more of Substance R might have been lost in the first, 
uncondensed portion of the distillate. In the following experiment no 
such loss could have occurred: 
Vacuum distillation of rancid beef fat. —A sample of highly 
rancid beef fat was distilled at a maximum pressure of 0.5 mm., a trap 
cooled in liquid air being employed to condense the most volatile por¬ 
tion of the distillate. 
Distillation was interrupted at 57 0 C. for the examination of the 
distillate. A small amount of material, having a strong odor of hep- 
tylic aldehyde, was recovered from the liquid-air tube. When suspended 
in a little water and tested with phloroglucin-hydrochloric acid a cream- 
colored precipitate was obtained, but no red color. The same result 
was obtained when the test was repeated after the previous addition of 
hydrogen peroxid. 
