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III. On the Theory of Types in Chemistry. 

 By T. Stekry Hunt, M.A. F.R.S* 



IN the Annalen der Chemie und Pharmacie for March 1860 

 (vol. cxiii. p. 293), M. Kolbe has given a paper on the 

 natural relations between mineral and organic compounds, con- 

 sidered as a scientific basis for a new classification of the latter. 

 He objects to the four types admitted by Gerhardt, namely, 

 hydrogen, hydrochloric acid, water, and ammonia, that they sus- 

 tain to organic compounds only artificial and external relations, 

 while he conceives that between these and certain other bodies 

 there are natural relations having reference to the origin of the 

 organic species. Starting from the fact that all the bodies of 

 the carbon series found in the vegetable kingdom are derived 

 from carbonic acid with the concurrence of water, he proceeds to 

 show how all the compounds of carbon, hydrogen, and oxygen 

 may be derived from the type of an oxide of carbon, which is 

 either C 2 O 4 , C 2 O 2 , or the hypothetical C 2 O. 



When in the former we replace one atom of oxygen by one of 

 hydrogen, we have C 2 O 3 H, or anhydrous formic acid ; the re- 

 placement of a second equivalent would yield C 2 O 2 H 2 , or the 

 unknown formic aldehyde; a third, C 2 H 3 ,the oxide of methyle; 

 and a fourth, C 2 H 4 , or formene. By substituting methyle for 

 one or more atoms of hydrogen in the previous formula, we ob- 

 tain those of the corresponding bodies of the vinic series ; and 

 it will be readily seen that by introducing the higher alcoholic 

 radicals, we may derive from C 2 O 4 the formulas of all the alcoholic 

 series. A grave objection to this view is, however, found in the 

 fact that, while this compound may be made the type of the 

 aldehydes, acetones, and hydrocarbons, it becomes necessary to 

 assume the hypothetical C 2 2 , H as the type of the acids and 

 alcohols. Oxide of carbon, C 2 O 2 , is, according to Kolbe, to be 

 received as the type of hydrocarbons, like olefiant gas (C 2 H Me), 

 while C 2 0, in which ethyle replaces oxygen, is C 6 ' H 5 , or lipyle, 

 the supposed triatomic base of glycerine. 



The monobasic organic acids are thus derived from one atom 

 of C 2 O 4 , while the bibasic acids, like the succinic, are by Kolbe 

 deduced from a double molecule, C 4 O 8 , and tribasic acids, like 

 the citric, from a triple molecule, C 6 O 12 . He moreover com- 

 pares sulphuric acid to carbonic acid, and derives from it by sub- 

 stitution the various sulphuric organic compounds. Ammonia, 

 arseniuretted and phosphuretted hydrogen, are regarded as so 

 many types ; and by an extension of his view of the replacement 

 of oxygen by electro-positive groups, the ethylides ZnEt, PbEt 2 , 



* Communicated by the Author. 



