• 



Reflections on some Miner alogkal Systems. 291 



iinless that the consistence of these principles be not so 

 necessarily united as to prevent their separation. For ex- 

 ample ; if a certain colour was an inevitable consequence of 

 the presence of a certain constituent part, we might adopt 

 the colour as a principle of classification, at the same time 

 with the presence or absence of this constituent part. But, 

 in doing this, we would admit at bottom but one single 

 principle as the basis of the system, since the existence of 

 the one would necessarily imply that of the other. As 

 M. Werner has admitted external characters to form the 

 basis of his system, at the same time that he explicitly de- 

 clares, that " all minerals which have essentially the same 

 constituent parts both with respect to quality and quantity 

 form the same species," we must suppose that he has dis- 

 covered certain connexions which exist between these 

 characters and the essential chemical composition of the 

 same mineral. The results of chemical analysis, never- 

 theless, do not correspond with this supposition; and the 

 science which unfolds the composition of minerals pro- 

 nounces it in a manner that does not agree with our re- 

 ceived ideas of the external characters. At the first glance 

 over the classification of M. Werner, we may perceive the 

 difficuliy in which this contradiction involves us; for the 

 desire of reconciling two things dissimilar in themselves, 

 has introduced an uncertainty which prevails over all its 

 parts. If we wish that this celebrated author should re- 

 main faithful to his principles, I see no other mode than 

 to suppose that he takes the testimony of external charac- 

 ters as the index of the chemical composition, rather than 

 the results of chemistry itself. 



Other authors, who have published works according to 

 the principles of M.Werner, tell us, that although this phi- 

 losopher considers all minerals which correspond in external 

 character and chemical composition, as belonging to the 

 same species, he does not pretend that his arrangement 

 should agree with the experiments of the chemist. This is 

 to speak at hazard, and to avow frankly that he regards 

 theoretical assertions as superior to experience, and the 

 system which he has adopted as preferable to the principles 

 of science. It would therefore only be when the chemi- 

 cal results agree with the external resemblances of minerals, 

 that they could occupy a place in this system. We see 

 sensible characters combined with chemical composition to 

 determine a species ; but if they do not agree with the 

 results of chemistrv, this science can be of no utility. 



T 2 ' Such 



