672 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1907. 
struct the initial edifice. It was thus that, in a really masterly 
achievement, he reconstructed fats, oils, and butters out of the glyc- 
erine and the acids derived from these fatty substances. The barrier 
which separated the reactions of the laboratory from the reactions 
of living organisms disappeared from this time on and the identity 
of biological and physico-chemical forces was thereupon established. 
The significance of such a demonstration may be readily understood. 
This was not all. It was at this time that the creative power of the 
chemist began to be manifested. As soon as Berthelot had discovered 
how to reproduce a fatty substance, stearine, for example, he had by 
the generalization of the process found the method of reproducing an 
infinite number of new fatty substances. Thus, while most of the 
animal or vegetable fats are formed essentially by the mixture of 
three or four well-defined chemical substances, the only ones found in 
nature, the chemist can make from them in his laboratory as large a 
number as he pleases. ‘ The synthesis of neutral fats,” said Berthelot 
in 1860, “ permits not only the formation of some natural fats already 
known, but it still further permits one to foresee the formation of 
innumerable analogous fats, which it will be easy hereafter to pro- 
duce in their entirety by virtue of the general law that governs their 
composition.” The domain of chemistry therefore becomes unlim- 
ited. The chemist himself, by synthesis, creates the object of his in- 
vestigation and in the thousands of new substances that are produced 
each year in the laboratories of the world, he distinguishes those 
whose properties can be used in the arts, in industry, in medicine, etc. 
The synthesis of fatty substances was only a partial synthesis; 
glycerine and the fatty generating acids were themselves produced 
from fats originally divided in two. In imitation of nature it was 
necessary to try to produce organic matters out of mineral substances. 
Taking carbon in the form of carbonic oxide, Berthelot combined this 
gas with potash and produced potassium formate. The barium 
formate, heated, lost methane, which by pyrogenation was able to give 
acetylene, ethylene, and ethane. From these carburets thus formed, 
Berthelot passed to the corresponding alcohols, methyl, ethyl, and 
their very varied derivatives. 
It is not, however, under the form of carbonic oxide that charcoal 
enters into plants; these build up the molecules of fatty matters, the 
hydrates of carbon necessary to their growth, with anhydrous carbon 
and water. Berthelot tried in vain to generate a primary carburet 
out of these two substances, so he replaced them with substances whose 
functions were most closely related to them, sulphuret of carbon and 
sulphuric acid; then in making both of these pass over copper, he 
obtained methane. By substituting iron for copper he obtained the 
same reaction from sulphuret of carbon and water. 
