[ 104. ] 



XII. On a New Chemical Theory. 

 By Archibald S. Couper, Esq.*' 



THE end of chemistry is its theory. The guide in chemical 

 research is a theory. It is therefore of the greatest im.- 

 portance to ascertain whether the theories at present adopted by 

 chemists are adequate to the explanation of chemical phsenomena, 

 or are, at least, based upon the true principles which ought to 

 regulate scientific research. 



Among those which have lately been developed, there is one, 

 on account of its apparently numerous merits, which particularly 

 claims investigation, and respecting which we deem that it would 

 not be unprofitable were either new proofs of its scientific value 

 furnished, or, on the contrarj', should considerations be adduced 

 establishing not only its inadequacy to the explanation, but its 

 ultimate detriment to the progress of science. I allude to the 

 system of tynes as advocated by Gerhardt. 



This system, striking alike for the breadth of its conception, 

 and the logical and consequent manner in which it has been de- 

 veloped, has been controverted from the point of view afibrded 

 by theories less far-reaching than the one under consideration, 

 and even based upon a one-sided and restricted appreciation of 

 certain chemical reactions. Tlie consequence is that this opposi- 

 tion has not impaired the favour with which the unitary system 

 has been received, but has rather tended to display it in a more 

 advantageous light. 



Imposing as this theory is, it is nevertheless all the more ne- 

 cessary to submit it to a strict investigation ; for there is nothing 

 so prejudicial in the search for truth as the blind spirit of con- 

 servation. A rational belief demands the test of a preliminary 

 doubt. 



There are two conditions which every sound theory must 

 fulfil:— 



1 . It nmst be proved to be empirically true. 



2. It must no less be philosophically true. 



I admit that this theory is for the most part empirically true, 

 that is to say, it is not contradicted by many of the facts of the 

 science. Evidence that this condition is only partially fulfilled, 

 is to be found — 



1. In the circumstance that the peroxides, for instance, do not 

 fit very satisfactorily into the types. 



2. The principle of double decomposition cannot well be 

 applied to the conversion of the anhydrous sulphuric acid into 

 the hydrate of that acid by the action of one equivalent of water, 



* Communicated bv tlic Author. 



