Mr. A. S. Couper on a New Chemical Tlieory. Ill 



C6 H6 and C^ H«, C^ H^ and C^ H'", &c. : from these last it is 

 especially evident that two is the combining gi-ade of carbon. 

 It becomes still more apparent when we compare the bodies 



cn 



C* H* and C* H^ CI, that is, C* H J&c. Many such proofs might 



be added, while on the other hand there are no instances con- 

 tradictory of this point. Hence the circumstance that it must 

 ever remain impossible to isolate a combinate of the foi'm C^ H* 

 or C* H^ &c. 



Carbon having only two grades of combination of two atoms 

 each, a fact which is easily traced throughout all organic che- 

 mistry, this inhei'ent property of the element may legitimately 

 furnish two grand types for all its combinates. 



The first type will be nC^ M*. 



The second type will be nC* M*— mM. 



As examples belonging to the first type, may be mentioned 

 the alcohols of the sethylic form, their aethers, the fatty acids, &c. 



Thus methylic alcoholhasthe formula C^.i.Trg , and sethylic 



^2-0-OH 

 alcohol, : "'H^ 

 C2...H3 



In these instances it will be observed, that for each double 

 atom of carbon the combining power is (4) four, which is the 

 ultimate limit of combination for carbon in all bodies yet pro- 

 duced. 



In the latter instance it is apparent, inasmuch as if the com- 

 bining limit of two C^s be each reduced by 3 in hydrogen or 

 oxygen, there still remains a combining power of one to each of 

 the two C^s which each expends in uniting with the other; 



C2...H3 . c^-O-OH 



therefore i , or what is the same thing, . '"H^ belongs 



C*- H^ Q2...JJS 



to the type nC^ M"*. 



Again, the inherent properties of the elements may be viewed 

 as dividing bodies into primary, secondary, tertiary, and so on 

 combinates. These may be termed so many orders of complicity. 

 Thus C'* li^" is a primary combinate, or it belongs to the first 



order of complicity ; but C.-.trs is a secondary combinate, 



or belongs to the second order of complicity. C^ 0^ and C* 0'' 

 are primary, while C2 0^20H and C^O^gOKa are se- 

 condary. 

 A primary combinate ia then nC* united to nM* or to nM*— mM* 



