LECTURE XII.] HISTORY OF CHEMISTRY. 235 



that he adopts Frankland's views, 48 which he further develops 

 and turns to account, especially in organic chemistry. He 

 only publishes the detailed statement of the opinions so arrived 

 at, in 1859, in a paper "On the natural relationship of organic 

 to inorganic compounds," 40 which contains many new ideas. 



Frankland had compared the radicals which contain metals 

 with the corresponding oxides. Kolbe now says that "The 

 chemical organic substances are wholly derivatives of inorganic 

 compounds, and are formed from these, directly to some extent, 

 by extremely simple substitution processes." Carrying out a 

 suggestion made by Liebig, 50 he derives the compounds of 

 carbon from carbonic acid, and those of sulphur from sulphuric 

 acid. The experimental bases of these opinions are the work 

 partly of Mitscherlich, 51 partly of himself (compare p. 2241/4?^.), 

 and partly also of Wanklyn, 52 who had succeeded in preparing 

 propionic acid from sodium ethyl and carbonic acid. 



Kolbe employed at this time, as well as long afterwards, the 

 atomic and equivalent weights of Gmelin, adopting at the same 

 time molecular weights for the majority of compounds agree- 

 able to the determinations of Gerhardt, Laurent, and William- 

 son. Accordingly he writes carbonic acid C 2 O 4 , and from this 

 anhydride he apparently derives the organic compounds such 

 as acids, aldehydes, ketones, alcohols, etc. I say " apparently," 

 for I shall afterwards show that it is not really so ; but I shall, 

 in the first place, state Kolbe's system in the form in which he 

 applied it. 



In carbonic acid, oxygen atoms are distinguished from one 

 another according to whether they are within, or outside of the 

 radical. The formula is therefore written (C. 2 O. 2 )Q.,, carbonic 

 oxide being regarded as the radical of carbonic acid. When 

 an atom of oxygen outside the radical is replaced by hydrogen 

 or an alcohol radical, the series of the fatty acids is obtained : 

 HO, H (C. 2 O,) O Formic acid, 

 HO, C 2 H 3 (C 2 O t ) O Acetic acid, etc. 

 When the second oxygen atom also is replaced by an alcohol 



48 Annalen. 101, 257. 49 Ibid. 113, 293. 50 Ibid. 58, 337. 51 Ibid. 

 9, 39- 5 ' 2 Journ. Chem. Soc. II, 103; Annalen. 107, 125. 



