674 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1907. 
Berthelot, moreover, made an exhaustive study of all the secondary 
chemical reactions which were produced at or near the electrodes. 
Upon these complex questions no chemist had so comprehensive a 
knowledge founded on experiment. Thus we may understand the 
skepticism with which he received all mathematical theories over- 
looking these secondary reactions. 
It was above all through the electric current that Berthelot obtained 
the most delicate syntheses. He showed that this current constituted 
the form of energy the most active and the most effective for securing 
the combination of substances. By its aid he was enabled to unite 
iodine with oxygen, to produce sulphuric anhydride from sulphurous 
gas and oxygen, to effect the absorption of nitrogen in considerable 
quantities by sulphuret of carbon, benzol, etc. Everyone still recalls 
_ the discovery of argon by Lord Rayleigh and Ramsay, who, after a 
number of years of trials of different sorts, were unsuccessful in 
obtaining a combination with this new gas. These scholars sent 
Berthelot several cubic centimeters of argon, and eight days after 
the eminent chemist announced to the Academy of Sciences that he 
had succeeded in uniting argon with sulphuret of carbon by means 
of the electric current. The small quantity of resinous matter ob- 
tained under these conditions, when sufficiently heated, in decompos- 
ing, regenerated argon with its initial properties. 
The contemporaries of Berthelot also did their share in developing 
chemical synthesis. It is sufficient to recall in particular his rival, 
Wurtz, to whose credit stand very important experiments on the 
synthesis of compound ammonias, of carburets of hydrogen, and of 
glycols. ‘“ It is with respect to the synthesis of glycols,” wrote Ber- 
thelot in 1884, “that a productive rivalry has arisen between us, in 
which each of us has developed the various resources of a nature as 
different from that of the other in its point of view as in its opera- 
tions. Works without number have sprung from these theories and 
in thirty years have transformed organic chemistry. Wurtz played 
a prominent part in this transformation.” 
Convinced of the unity of natural forces, Berthelot tried to adapt 
the laws of chemical transformations to the laws of mechanics. He 
devoted himself to developing a new science, thermochemistry, from 
which was derived chemical mechanics. Lavoisier and Laplace, 
Hesse, Favre and Silbermann had already succeeded in taking several 
calorimetric measurements, but the principle of equivalents in the 
order of chemical reactions was a new idea which was to be estab- 
lished with precision by the researches of Berthelot. At this time 
Regnault had completed his numerous calorimetric experiments and 
had secured for this division of physics an accuracy theretofore un- 
known. Regnault obtained this accuracy through a more complex 
apparatus, by superimposing in a certain way on the principal appa- 
