136 HISTORY OF CHEMISTRY. [LECTURE VIII. 



Dumas to his opinions, and we find the two savants conjointly 

 publishing a scientific treatise 25 in which they announce that 

 thenceforth they wish to elaborate organic chemistry with 

 united energies and from the same point of view; to have 

 analysed in their laboratories all the substances not yet 

 examined by them ; to open up, by the aid of their pupils, 

 additional lines of investigation in the most varied directions ; 

 and to subject the work of others to a rigid criticism and check. 

 But the union only endures for a short time : it is terminated 

 in a year, and each returns to special paths, which diverge 

 more and more. In 1840 the two are again hostile towards 

 each other, although perhaps more careful in their assertions 

 and more polite than previously. 



Dumas had made observations in the meantime which 

 caused him to break away from all traditions, to abandon 

 dualism and the electro chemical theory, and to express views 

 that Berzelius especially attacked most vigorously. The latter, 

 who up to this time had taken the most important part in the 

 development of the science, holding his opponents in check by 

 means of his theories, and who had struggled for the ascendency 

 with Liebig and Dumas, now tries, ineffectually, to oppose his 

 ideas to those of Dumas and of Laurent. He relies upon 

 unestablished hypotheses, which only later, at Kolbe's hands, 

 receive a real foundation, and acquire thereby a scientific 

 significance. 



Before turning to this period, with its theories of substitu- 

 tion, of nuclei and of copulae, we must still consider a further 

 development of radicals in the earlier sense, with which the 

 various notions respecting alcohol and the compounds derived 

 from it are brought to a close. 



Regnault, in his examination of the oil of the Dutch chemists, 

 had found that this substance loses the elements of hydrochloric 

 acid when it is distilled with potassium hydroxide, and that it 

 yields a new substance of the composition C 4 H 6 C1 2 . 26 This he 

 regards as the chloride of the radical aldehydene, C 4 H 6 , and 



25 Comptes Rendus. 5, 567. <26 Ann. Chim. [2] 59, 358 ; Annalen. 15, 60. 



