156 
MR. BRODIE ON CEROTIC ACID. 
The products of this distillation prove also that we must look to some other body 
than the cerin for the source of the margaric acid, or the acid resembling that sub- 
stance which has been found in the wax distillate, and for the origin also of the 
paraffin, of which only traces can be found even on the distillation of the impure 
cerin. 
The existence of a free acid in wax is a fact to which we have no parallel in the 
constitution of any known fat, and although the reactions, which I have given, left 
little doubt upon my mind that in the wax the acid was in this condition, it yet ap- 
peared to me desirable to procure it from the wax by simple crystallization. By 
patience this may be accomplished. The cerin analysed by M. Lewy melted at 
62°-5 C. I have stated that by means of alcohol this substance may be procured of 
a melting-point of 72°. If this substance of 72° melting-point be repeatedly dissolved 
and crystallized out of a large quantity, not of alcohol, but of ether, the melting-point 
can be raised to 78°, in which state the substance is highly crystalline, and has all 
the appearance of the acid as procured by other means. 
0'25625 grm. of this gave 0*7435 COg and 0*3005 HO, 
which gives in 100 parts — 
Carbon . . . . 79’ 13 
Hydrogen . . . 13*20 
Oxygen . . . . • 7 67 
100*00 
Both the melting-point and the analysis perfectly agree with the melting-point and 
analysis of cerotic acid, which have been already given, and with its formula. 
It is certainly a strange fact that the presence of this body in the wax should so 
long have escaped the notice of chemists. The wax however is a complex substance, 
and the cerotic acid to be obtained in purity has to be separated from many other 
bodies which disguise its nature and reactions. 
Should any chemist be induced to verify the results which I have given, I must 
beg him also rigidly to observe the methods I have laid down for the preparation and 
purification of the substances, for errors which are slight in the analysis of the sub- 
stance and which neither the analysis nor melting-point detect, become of great im- 
portance when the transformations of the substance are investigated, and its atomic 
weight is to be determined. 
The alcoholic extract, out of which the cerotic acid has crystallized, contains, 
although in very small quantities, yet another acid. If to the solution an alcoholic- 
solution of acetate of lead be added, a precipitate of a lead salt is produced : this 
salt is readily distinguished from the salt of the cerotic acid as it is dissolved on 
boiling the alcoholic solution, out of which, on cooling, it will separate in crystalline 
grains. This substance is contained in very small quantity in the wax. It resembles 
in appearance margaric acid. I have analysed this acid and one of its salts. These 
