155 
MR. BRODIE ON CEROTIC ACID. 
A question suggests itself, If it be true that this acid is volatile, and it be also true 
that it exists in the wax in an uncombined state, how has it happened that it has 
never been discovered among the products of the distillation of wax which have been 
so often examined ? 
In truth, it is a remarkable fact, that while this acid, when heated in a nearly pure 
state, as separated from the lead salt, distils over nearly unaltered, the same substance, 
when distilled in an impure state, as separated, namely, by alcohol from the wax, 
and mixed, as in this case, with other wax matter, which is decomposed by heat, 
itself suffers decomposition. In the course of this investigation other examples have 
occurred to me of similar facts. 
About 3 oz. of the cerin, melting at 70° C., from which this acid can be precipitated 
by acetate of lead, was distilled. The first portions of the distillate consisted entirely 
of oil. Towards the end a small quantity of solid matter appeared. The oil, on stand- 
ing, separated into two portions : the lower part was withdrawn by a pipette, being 
but a small portion, say one-twentieth of the whole. The upper portion was boiled 
with potash, only a very small portion of acid however was separated in this manner. 
The soap was drawn off by a syphon, and the oil washed out with water. On being 
washed with strong alcohol the oil dissolved, almost entirely, leaving only a small 
portion of solid matter of the appearance of paraffin. This oil consists of a mixture 
of oils of different boiling-points, which were separated as far as possible by rectifi- 
cation, but during the distillation the boiling-point kept constantly rising, and I 
could obtain no oil in which it was absolutely constant. 
Three of these oils, of the respective boiling-points of 210° to 220° C., 230° to 250° 
C., and 250° to 274° C., were analysed. By far the greater portion of this whole di- 
stillate went over between 230° and 250° C. The results of these analyses were — 
In the case of the first oil, 
(1) . 0'2676 grm. gave 0*826 carbonic acid and 0*3307 water. 
In the case of the second oil, 
(2) . 0*2629 grm. gave 0*8127 carbonic acid and 0*3325 water. 
In the case of the third oil, 
(3) . 0*2697 grm. gave 0*8443 carbonic acid and 0*341 water, 
giving in 100 parts — 
Carbon . . 
• 
00 
II. 
84*30 
III. 
85*37 
Hydrogen . 
. . 13*73 
14*05 
14*05 
Oxygen . . 
. . 2*10 
1*65 
0*58 
100*00 
100*00 
100*00 
The amount of oxygen therefore diminishes as the boiling-point rises in these oils, 
the last oil being nearly pure hydrocarbon. It is useless to reckon out formulae for 
them : I give however the analyses to point out the source of the oils in the wax di- 
stillate, and to account for the disappearance of the cerotic acid in that product. 
X 2 
