Marcu 28, 1907 | 
NATLORE 
513 
thesis on glycerin and the fats, published in 1854. 
Chevreul had compared the fats to compound ethers, 
or esters, as we should now call them. Berthelot 
showed that the relation of glycerin to ordinary 
alcohol was comparable to that of phosphoric acid 
to nitric acid, thus introducing the important notion 
of polyatomic alcohols into chemistry. By a curious 
slip, inconsistent with the facts he had discovered, 
Berthelot compared the three series of glycerin esters 
to the orthophosphates, pyrophosphates, and meta- 
phosphates, instead of to the neutral and “‘ acid” 
salts of orthophosphoric acid. It was reserved to 
Wurtz, his great rival, to give the fullest interpret- 
ation and extension to his discovery. 
The next question to which Berthelot devoted him- 
self was a larger one. Gerhardt, who in the ‘forties 
had contrasted the analyses of the chemist with the 
organic syntheses of nature, effected by the help of 
“vital force,’’ already in 1853, in the introduction to 
his ‘‘ Traité de Chimie organique,’’ described as the 
object of chemistry :—‘‘ la connaissance des moyens de 
composer tous les corps, la connaissance des moyens 
de décomposition n’en étant que le préliminaire 
obligé.’’ But at that time the only organic com- 
pounds that had been synthesised from their elements 
were urea, by Wohler, and acetic acid, by Kolbe. 
Berthelot set himself the great task of synthesising 
from their compounds the fundamental organic com- 
pounds, marsh-gas, formic acid, methyl and ethyl 
alcohol, acetylene, benzene—and succeeded. His 
work overthrew the ‘‘ vital force ’’ theory as applied, 
not, indeed, to living matter, but to its non-living 
products. It forms the basis of those syntheses which 
have perhaps given to the chemistry of the nineteenth 
century its greatest prestige in the eyes of the world. 
In his work on the fats, Berthelot had shown that 
they could be produced by the direct action of 
glycerin on the fatty acids, provided that time were 
given; it was characteristic of the man to generalise 
from this single discovery. In his worl with his 
pupil, Péan de St. Gilles, on chemical affinity, pub- 
lished in 1862-3, he first introduced into. chemistry 
the study of rates of reaction and of reversible re- 
actions. Few single researches in the history of 
chemistry have been more fruitful of results. 2 
He next set himself a task comparable to the work 
on organic synthesis. C. L. Berthollet in the early 
years of the nineteenth century had written a famous 
treatise on chemical statics; it was Berthelot’s ambi- 
tion to lay the foundation of chemical mechanics as 
a whole by a systematic study of the heat-changes 
involved in chemical reactions. Andrews, Hess, 
Favre and Silbermann, and others had carried out 
isolated investigations in this domain, but Berthelot, 
and almost simultaneously Thomsen, the Danish 
chemist, set out to investigate the whole field of 
thermochemistry systematically. In his ‘* Mécanique 
Chimigque fondée sur la Thermochimie,’’ published in 
1879, Berthelot gives the result of fifteen years’ 
assiduous work. Full of brilliant discoveries of de- 
tail, of ingenious methods of experiment and calcu- 
lation, the work cannot be said to have realised to 
the full the ambitions of its author. The ‘‘ principle 
of maximum work,’’ which he regarded as_ his 
greatest generalisation, is incomplete. But his work 
is, nevertheless, monumental in extent, and forms 
the necessary starting point for all fresh researches 
on the subject. In 1897 he published a vast collection 
of thermochemical data under the title ‘‘ Thermo- 
chimie, Données et Lois numériques.’’ 
In one branch of thermochemistry, that of ex- 
plosions, Berthelot’s discoveries are as novel as they 
are fundamental. Working mainly with his pupil 
Vieille, he found that when an explosive mixture or 
compound is fired, the flame proceeds through the 
NO. 1952, VOL. 75 | 
mixture at a gradually increasing rate until a maxi- 
mum rate is attained of which the value depends on 
the chemical composition of the explosive. This. is 
the phenomenon of the “‘ onde explosive,”’ or explosion 
wave, especially familiar in this country through the 
remarkable work of Dixon, carried out subsequently. 
It was in the course of his work on explosive mixtures 
that Berthelot invented the well-known calorimetric 
bomb, an extremely simple and accurate instrument 
for determining the heats of combustion of organic 
compounds. 
The problems of vegetable chemistry began to 
interest Berthelot in 1876, when he showed that 
nitrogen could be made to combine directly with 
carbohydrates under the influence of the silent electric 
discharge. Later he found that the microbes of the 
soil played an important part in the fixation of 
nitrogen in the vegetable tissues—a discovery to 
which the work of Hellriegel and Wilfarth on legu- 
minous plants gave the most brilliant confirmation. 
In 1884 a fine laboratory was built for him on the 
heights of Meudon, and here, with the devoted and 
able collaboration of M. G. André, he carried out the 
vast series of researches on vegetable chemistry re- 
corded in the four volumes on ‘‘ La Chimie végétale 
et agricole,’? published in 1899. 
Berthelot’s work in the history of chemistry is on 
the same kind of scale as his experimental work. In 
a first book, ‘‘ Les Origines de 1’Alchimie,’’ he traces 
alchemy to its origin in a combination of the ideas 
of Egyptian metal-workers (who from the practice 
of making alloys naturally desired to economise the 
use of the precious metals in their production) and 
of the Greek ideas of the transmutation of elements 
current in the school of Alexandria. In 1887-8 he 
published a more comprehensive work, in collabor- 
ation with C. E. Ruelle, the ‘‘ Collection des 
Alchimistes grecs.’’ This was followed in 1893 
by a similar work, ‘La Chimie au Moyen-age,”’ 
which deals with the Syriac and Arabic alchemists, 
translated by MM. Rubens Duval and Houdas. The 
author showed that the Latin works previously 
attributed to Geber (or Djaber, as he should be 
called) were late forgeries, and published authentic 
texts of the famous alchemist. These he supple- 
mented in his last work, ‘‘ Archéologie et Histoire 
des Sciences” (published in 1906), by printing the 
Latin translation of another work of Geber, the 
‘Liber de Septuaginta,”’ of which the Arabic original 
has been lost, together with a number of fresh 
memoirs on medizval chemistry and on the composi- 
tion of metallic specimens of Egyptian, Chaldaic, 
Persian, and Roman origin. On the more modern 
history of chemistry he published a book on Lavoisier, 
“La Révolution chimique ’’ (1890), containing ex- 
tracts from Lavoisier’s note-books, and “La 
Synthése chimique ”’ (1875). 
Besides these works and practical treatises on 
calorimetry and gas analysis, he published a number 
of volumes of essays—‘ Science et Philosophie ”’ 
(1886), ‘‘Science et Morale ’’ (1897), ‘ Science et 
¥ducation”’ (r1g01), ‘‘Science et Libre-Pensée WY 
(second edition, 1905); and the correspondence with 
Ernest Renan, who in his ‘‘ Souvenirs d’Enfance ”’ 
has left so interesting an account of the beginnings 
of the life-long friendship of the two men, was issued 
in 1898. 
The ‘‘ Cinquentenaire scientifique de M. Berthelot em 
gives an account of the jubilee celebration held at the 
Sorbonne on November 24, 1901, when, in the pre- 
sence of the President of the French Republic and the 
great officials of State and of the learned bodies of 
France, M. Berthelot received the congratulations of 
the academies of the world. ‘‘ Dés que vous abordez 
une question,’’ said Moissan in addressing him on 
