GerhardPs Organic Chemistry. 93 



Art. XII. — Review of 



of M. Charles 



ERHARDT 



This book appeals with peculiar claims to the notice of all 

 interested in the progress of chemical science. Organic chemis- 



try has made great progress during the last few years ; but until 



the publication of the Precis, with the exception of Liebig's ex- 

 cellent Traite de Chimie Organique, no systematic work embra- 

 cing the results of the last decade had appeared. This is to be 

 ascribed to the great difficulty of classifying the immense array 

 of facts, and harmonizing the various conflicting theories — a task 

 indispensable as a preparation for such a work and at the same 

 time exceedingly delicate. 



Liebig in his Traite assumed as the basis of his system, the 

 theory of compound radicals, and commences with the asser- 

 tion, that "organic chemistry is the chemistry of compound radi- 

 cals." This was a most ingenious application of the electro- 

 chemical philosophy of Berzelius to the investigation of this class 

 oi compounds, and was supported by so many analogies as to 

 render it very probable ; at the same time it admitted the appli- 

 cation of the received nomenclature to these bodies. These rad- 

 icals are generally however purely hypothetical, and when we 

 are able to isolate substances having the composition assigned to 

 them, they are found to possess none of the properties which 

 theory would require. Recent experiments have shown that 



by Liebig, 



ascribed 



pound 



radical. Cyanogen and kakodyle must however be excepted, as 

 compounds which comport themselves in many respects like ele- 

 mentary bodies. 



The progress of discovery has shown, that this hypothesis is 

 but poorly adapted to form the basis of a system of classification, 

 lor the discovery of nearly every new body requires the assump- 

 tl °n of an imaginary compound to explain its reactions in accord- 

 ance with the theory of radicals ; and so uncertain are the princi- 

 ples which are to direct us in the application of this theory, that 

 dl fferent chemists often assign very different rational formulas 

 to the same compound. There have been not less than seven 

 different formulas proposed, to express the arrangement of the ele- 

 me nts in alcohol ; each author seeking by his own to explain 

 some practical relation. Thus Dumas regards it as the bi-hy- 

 drate of olefiant gas ; Liebig as the hydrated protoxyd of ethyle, 





