182 M. Dumas on the Law of Substitutions, and the 



The chemistry of Lavoisier and its nomenclature seemed 

 then to have foreseen and prepared the electro-chemical theory, 

 which has had nothing else to do than to call one of these an- 

 tagonist bodies the positive element, and the other the nega- 

 tive element. 



But let us not lose sight of the great discovery of Lavoisier ; 

 it is the discovery of the elements. This is the fundamental 

 principle by which he revived chemistry and natural philoso- 

 phy. Not a truth of this order is discovered without leaving 

 its impress on all our thoughts ; and for the same reason that 

 Lavoisier had established that all the bodies of nature might 

 be formed by means of some elements, he would be led to de- 

 fine the compound bodies by the elements which compose them, 

 and there, in fact, is the principle that our nomenclature has 

 appropriated. 



Now not only is the nomenclature of Lavoisier no longer 

 sufficient for us, but it expresses a system of ideas quite con- 

 trary to that which we seek to cause to prevail. 



It is no longer sufficient for us, because in organic che- 

 mistry thousands of combinations are produced with three 

 or four elements, and consequently those could not lend 

 themselves to name all the compounds which result from 

 them. 



It is positively contrary to the system of ideas explained 

 above, in this, that it derives the notion of the bodies from the 

 nature of its elements, whilst the latter have only what may be 

 called a secondary interest in the classification. 



Each type must have a name, and this name should be 

 found in the numerous modifications which it may undergo, 

 so that it should never disappear so long as the type itself is 

 not destroyed. 



It is on this principle that I have already formed the follow- 

 ing names : acetic acid and chloracetic acid, ccther and chlor- 

 cether, olefiant gas and chlorolefiant gas ; names, the object of 

 which is to set forth, as may be seen, the permanency of the 

 types, notwithstanding the intervention of chlorine- in the com- 

 pounds. 



The theory of types views these bodies in some degree as 

 casts from the same mould, with different materials. It would 

 have the nomenclature always recal their fundamental molecu- 

 lar arrangement, and that it should be put in the first line, 

 whilst the nomenclature of Lavoisier applies itself to the ma- 

 terial, brings out the nature of it, and places this notion 

 first. 



The theory of types tells you, here is alum of chromium ; 



