112 Mr. A. S. Couper on a New Chemical Theory. 



in such a manner that the combining energy of the complement 

 (nM'', &c.) either potentially or actually does not extend beyond 



A secondary combinate is one in which the combining energy 

 of the complement is not all expended upon nC^, but is extended 

 further to one or more elements. 



On the same principle there are tertiary combinates^ &c. 



These orders of complicity ought in reality to be subdivided. 

 This, however, I do not think it necessary for the present to 

 enter upon. It will now be understood why an alcohol belongs 

 to the type nC^ M"*, and on the same principle why a free aether 



belongs to the same type, thus : — H'^H^"" , while they are 



C2...H3H3...C2 



at the same time secondary combinates. 



A secondary combinate, that is to say, a body belonging to 

 the second order of complicity, is, as will be understood from the 

 principle which forms the ground of the rational theory, a direct 

 consequence of an inherent property of one or more of the ele- 

 ments which form the complement to the carbon. 



In the instance before us, it is a certain property of the oxygen 

 which is the cause of the secondary combinate. This property 

 is the affinity which one atom of oxygen in combination always 

 exerts towards another atom of oxygen likewise in combi- 

 nation. 



This affinity is modified by the electric position of the element 

 to which the respective atoms of oxygen arc bound. From this 

 property results the fact, that in organic combinates the atoms 

 of oxygen are always found double. 



For instance, the combining limit of oxygen being two, when 

 ^2...0... 

 two molecules of .- "H^ are set at liberty, the free affinities of 



the oxygen instantly produce the union of these molecules. The 

 cause of the union of two molecules of C- H^ has been already 

 remarked. In the two cases, the causes of the union of the 

 respective molecules are in so far different, that the one is the 

 result of a property of the carbon, while the other is the result 

 of a property of the oxygen. 



The view here adopted of the nature of oxygen is, I am con- 

 vinced, alone in conformity with the reactions where the proper- 

 ties of this body develope themselves. 



The vapour of anhydrous sulphuric acid, for instance, is con- 

 ducted into anhydi'ous sether. The following will then be the 

 reaction : — 



