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LXV. Considerations on the two Memoirs of Sir B. C. Brodie 

 on the Calculus of Chemical Operations. By M. A. Naquet*. 



IT is not our intention here to express a complete judgment 

 upon the work of Sir B. C. Brodie. This work comprises 

 a mathematical part, of which we are not competent to judge, 

 and a chemical part, upon which we have the right of pro- 

 nouncing. It is with the latter alone that we mean to occupy 

 ourselves here. 



We may begin by saying that whatever may be the final 

 judgment pronounced upon the work of Sir B. 0. Brodie, that 

 work appears to us remarkable ; and it is that which has in- 

 duced us to make it known to the French public. 



The application of Algebra to the experimental sciences, the 

 substitution of " theories," based upon facts and demonstrated 

 laws, for " systems " which only rest upon metaphysical hypo- 

 theses, is the end towards which science ought to tend ; and if 

 systems are necessary for the arrangement of phenomena, and 

 for the discovery of new phenomena in those points where the 

 progress of science has not yet allowed them to be replaced 

 by theories, this substitution ought, nevertheless, to be effected 

 as soon as practicable. 



We will say at once that Sir B. Brodie is unjust in denying 

 the discoveries which are due to the atomic notation. It is 

 by means of this notation and the probabilities deduced by it 

 that a number of syntheses have been effected — such, for ex- 

 ample, as the synthesis of the phenols, those of the acids of the 

 salicylic series, of secondary and tertiary ammonia compounds, 

 etc. etc. How could it, in fact, be otherwise ? As M. Dumas 

 says, in his i Lecons de philosophic chimique,' a hypothesis 

 created for the explanation of twenty phenomena, to which it is 

 adequate, is necessarily applicable to ten, twenty, thirty other 

 unknown phenomena on the track of which it places the ob- 

 server. But, while fully recognizing the superiority of a 

 " theory " over a system, we refuse to abandon our system 

 unless the theory be complete enough to render all the services 

 which the system has rendered. It does not appear to us that 

 at present the notation of Sir B. Brodie has gone so far as to 

 be able completely to replace the existing notation ; but I do 

 not consider these reasons sufficient to condemn it* 



When Gerhardt modified the notation in use before his 



* M. A. Naquet has translated into French the two memoirs referre d 

 to, on which translations the critical observations of M. A. Naquet are 

 "based. These have been translated into English under my supervision. — 

 B. C. B. (Moniteur Scientifique du Docteur Quesneville, Nov. 1878, 

 March and April 1879.) 



