226 HISTORY OF CHEMISTRY. [LECTURE XII. 



the adherents of the theory of types who, with the excep- 

 tion of Williamson, 17 write reaction or decomposition formulae 

 only. 



With the assumption of distinct atomic groups in complex 

 substances the idea of the possibility of their isolation was also 

 combined, and thus we find Kolbe and Frankland, in 1848, 

 engaged in experiments which have for their aim the separation 

 of radicals ; ls in particular, it appeared to Kolbe extremely 

 desirable to decompose acetic acid into methyl and oxalic acid, 

 of which it was the conjugated compound. He succeeds in 

 isolating one, at least, of the radicals lv) by aid of the electrical 

 current. Under the influence of this agency, acetic acid splits 

 up into methyl and carbonic acid. According to Kolbe, the 

 reaction took place in such a manner that the conjugated 

 groups first separated from one another, and that the oxalic 

 acid was then converted into carbonic acid at the expense of 

 the oxygen of the water ; and the simultaneous evolution of 

 hydrogen appeared to confirm this view. 



The preparation of methyl cyanide by heating ammonium 

 acetate with phosphoric anhydride, 20 discovered a short time 

 previously by Dumas, told in favour of the views of Kolbe 

 and Frankland, and so did the conversion of the nitriles into 

 the corresponding acids, which was carried out by the latter 

 chemists themselves.- 1 



Upon his isolation of ethyl from ethyl iodide by means of 

 zinc,' 22 it appeared to Frankland that he had removed every 

 doubt as to the accuracy of his and Kolbe's mode of regarding 

 compounds. The ethyl theory was now to resume its old place, 

 in the form stated by Liebig in 1835. According to Frank- 

 land : " The isolation of four of the compound radicals belong- 

 ing to the alcohol series, now excludes every doubt of their 

 actual existence, and furnishes a complete and satisfactory 



17 Journ. Chem. Soc. 4, 350. l8 Ibid. I, 60; Annalen. 65, 269. 

 10 Journ. Chem. Soc. 2, 157; Annalen. 69, 257. ao Comptes Rendus. 

 25, 383 and 473 ; Annalen. 64, 332. - l Annalen. 65, 288. " Journ. 

 Chem. Soc. 2, 263; Annalen. 71, 171. 



