ON THE STATE OF ORGANIC CHEMISTRY. 



21 



atomic weight of oxygen : we refer to Limpricht*, Kolbef, and Couper^. 

 The first of these chemists founds his objection to the greater atomic weight 

 of oxygen upon the fact that some salts crystallize with a quantity of water 

 containing an odd multiple of 8 parts of oxygen. To this it may be 

 answered, that the function of water in crystallized salts is not sufficiently 

 well understood to warrant our drawing conclusions of any importance from 

 the quantity of it contained in any particular substance, and that no reason 

 has yet been shown why several atoms of a salt should not crystallize with 

 one atoirf of water, as well as several atoms of water with one atom of a salt. 



The objections of Kolbe are founded on more general considerations. By 

 comparing the composition of the so-called organo-metallic bodies with that 

 of the inorganic compounds of the metals which they contain, he came to 

 the conclusion that the metallic oxides are typical of the compounds of the 

 metals with organic radicles. 



For instance, taking the atomic weight of oxygen at 8, and writing oxide 

 of zinc and arsenious anhydride ZnO and AsO 3 respectively, we get the 

 following comparison of formulae : — 



Oxide of zinc Zn 

 Zinc-ethyl .. ZnEt=ZnC 2 H 5 



Arsenious anhydride As O 3 

 Oxide of arsenomo- 



nomethyl AsO 2 Me = As0 2 CH 3 



Oxide of kakodyl.. AsO Me 2 =AsOC 2 H e 

 Termethylarsine .. As Me 3 =AsC 3 H°. 



Admitting the accuracy of such formulae, it was natural to extend similar 

 views to those compounds of carbon which do not contain metals. Accord- 

 ingly, Kolbe regards carbonic anhydride C 0\ the highest known oxide of 

 carbon, as the type of a large number of other carbon-compounds. Accord- 

 ing to him, the replacement of I atom oxygen in carbonic anhydride by 1 

 atom hydrogen, or 1 atom of an alcohol-radicle, gives monobasic acids, such 

 as those of the acetic and benzoic series ; the like replacement of 2 atoms oxy- 

 gen gives aldehydes and acetones ; the replacement of 3 atoms oxygen gives 

 ethers ; and lastly, the replacement of all the oxygen gives alcohol-radicles 

 and their hydrides. The following illustrations will make this clearer: — 



O 



Type 



I. II. 



CH 3 



( 

 O l 



o 



Formic Acetic acid Aldehyde, 

 acid (anhydrous), 

 (anhy- 

 drous). 



It must certainly be considered fortunate for the interests of science that 

 Professor Kolbe should himself have extended his theory to the purely 

 organic compounds of carbon; for these being the precise substances of 



* Limpricht, Grundriss der organischen Chemie (1855). 



t Ann. Chem. Pharm. ci. 257. The same views were also advocated by Fraiikland in a 

 lecture delivered at the Royal Institution, May 28th, 1858. (See Journ. Roy. Instit.) 

 X Ann. Chini. Phys. [3] liii. 4G9 ; Ann. Chem. Pharm. ex. 46. 



