ON THE COMPOSITION OF STEARIC ACID. 49 
In the first Number of the 33rd volume of the Annalen der 
Chemie und Pharmacie, Professor Liebig published a memoir on 
the state of our knowledge of the constitution of the fat acids, 
in which he showed its uncertainty and incompleteness, as well 
as what would probably be the result of a renewed investigation, 
and it was at his request that I undertook the following work in 
his laboratory. 
The investigation of stearic acid was the first thing to be 
effected, for although the best known, there yet remained some 
doubt concerning the products of its distillation, and it at all 
events must be the basis of all ulterior inquiry. 
In order to study the products of the distillation of stearic 
acid, that obtained from ox fat in the stearic acid manufactory of 
Merck, of Darmstadt, and which is a raw stearic acid, quite white, 
crystalline, fusible at 56° C.* (133° F.), and free from wax, was 
dissolved in alcohol and crystallized. The crystals first depo- 
sited were again dissolved in alcohol, and this treatment repeated 
seven or eight times, until by the expulsion of the alcohol by 
evaporation with water, solution in potash, and subsequent se- 
paration by means of hydrochloric acid, the melting point of the 
acid was constantly 70° C. (158° F.). 
_ Although this investigation was undertaken under the firm con- 
viction that the numerical results of Chevreul were correct, yet in 
order to place it beyond doubt that the acid submitted to distilla- 
tion was really stearic acid, and identical with that of Chevreul, 
an ultimate analysis with oxide of copper was instituted. 
Chevreul found 100 parts of the hydrated stearic acid to con- 
tain 
Carbon. sire) (5 eyes «9774200 
Hiygnoret at ban ease 
Quyeen agi .ters «1201488 
however, 0°624 gr.t of stearic gave to me 1°727 gr. carbonic acid, 
ord The melting point was here, as well as in all the succeeding cases, deter- 
mined as follows : a glass tube was drawn out before a lamp until it was very 
thin and capillary, into this the melted substance was drawn up by the mouth ; 
the tube thus charged and a thermometer were then placed in water of a mo- 
derate temperature, which was raised by degrees; finally, that point was taken 
as the melting point at which the whole of the contained substance became 
fluid, that is, transparent. By means of water of a somewhat lower tempera- 
ture the point of solidification was rendered obvious, and this was commonly 
from 1° to 2° C. lower than that of fusion. 
+ Gr. in this case, as well as all those which follow in this memoir, refers to 
grammes and not to grains. 
VOL, IIT. PART IX. E 
