LECTURE VIII.] HISTORY OF CHEMISTRY. 149 



On scarcely any side did the nucleus theory meet with 

 acceptance. Dumas made use of much of it in advancing the 

 theory of types, and although in doing so he mentions Laurent, 

 still opinions which unquestionably were first stated by the 

 latter, were ascribed to Dumas. No doubt, they met with 

 acceptance earlier on account of the superior authority and 

 position of Dumas. 



Liebig, however, expressed himself very forcibly against 

 Laurent, 51 and he was not altogether unjustified in his charges. 

 In the application of his theory Laurent incurred blame for 

 many arbitrary proceedings, which Liebig knew how to point 

 out with much effect. Liebig further attacks the facts dis- 

 covered by Laurent and employed by him in support of his 

 opinions ; and these are likewise not always able to withstand 

 the keen criticism applied to them. 



Much more violent still were the attacks of Berzelius, 52 

 which he erroneously directed against Dumas. The view that 

 negative chlorine could take the place of positive hydrogen, 

 without altering the nature of the product, was wholly inadmis- 

 sible with the author of the electro-chemical theory. He makes 

 every conceivable endeavour to bring the constantly increasing 

 number of substitution products into harmony with his theories. 

 I shall postpone, however, the detailed consideration of his 

 views until a subsequent lecture, and shall close this one with 

 an observation of Gerhardt's, 53 which enables us to recognise 

 the clear and intelligent perception of this chemist, who at the 

 time was still quite a young man. 



Laurent's formula for Dutch oil was C 4 H 6 C1 2 + H 2 C1 2 . By 

 treatment with chlorine this substance was said to be converted 

 into chloride of carbon, C 4 C1 12 . 54 According to Gerhardt, 

 Laurent's formula is inaccurate because it assumes the decom- 

 position of hydrochloric acid by means of chlorine, accompanied 

 by the re-formation of hydrochloric acid. 



51 Annalen. 25, I. 5 ' 2 Compare Comptes Rendus. 6, 629 ; and 



Berzelius' Jahresbericht 1840, 361. 53 J. pr. Chem. 15, 17. 54 Phil. 

 Trans. 1821, 47. 



