230 HISTORY OF CHEMISTRY. [LECTURE XII. 



and the sulpho-acids, is preserved. Thus, we have, for 

 example, 



HO(C 2 C1 8 )S 2 , 5 HO(C 2 Cl 3 fc 2 , 8 . 



Chlorkohlenunterschwefelsaure Chlorkohlenoxalsaure 



(Trichlormethyl-sulphonic acid). (Trichloracetic acid). 



The paper of Kolbe referred to here forms the complete 

 foundation of a chemical system, from which I have only been 

 able to select the most important parts. In it the attempt is 

 made to maintain the radical theory, but the fundamental 

 conception of this theory has undergone important changes. 

 Thus the capability of radicals to undergo substitution was 

 now necessarily admitted, and, with this admission, the radicals 

 ceased to occupy an exceptional position. Besides this, the 

 conjugated radicals had been tacked on to the theory, and 

 these had not been by any means sharply defined. 



Kolbe tries to rescue the electro-chemical theory, but he is 

 obliged to make very important admissions to the opponents 

 of Berzelius. Opposite electrical conditions are still supposed 

 to exist between the constituents of a compound ; but which 

 is the positive and which the negative constituent remains 

 undecided, simply because Kolbe assumes that the same 

 element may possess different electro-chemical properties an 

 assumption for which justification is found in the existence of 

 elements in allotropic conditions. But the very admission 

 which Kolbe makes, becomes the central point of the con- 

 troversy ; and it is only demonstrated anew that the theory of 

 Berzelius, in the old form, is no longer tenable. 



In addition to Frankland, Kolbe had only a few special 

 adherents, and when the former made important changes in 

 the notions with respect to coupling, in 1852, Kolbe, having 

 regard to the facts, was obliged to modify his views. The 

 new hypotheses which he advances, now approach much more 

 nearly to the notion of types, even although his mode of 

 naming and of formulating substances is peculiar to himself. 

 As regards its fundamental principles, the system of Kolbe 

 ranks below that proposed by Gerhardt, particularly because 

 it does not contain any distinction between molecule, atom, 



