268 HISTORY OF MINERALOGY. 



published his Essay to establish a purely Scientific 

 System of Mineralogy, by means of the Application 

 of the Electro-chemical Theory and the Chemical 

 Doctrine of Definite Proportions. It is manifest 

 that, for minerals which are constituted by the law 

 of Definite Proportions, this constitution must be 

 a most essential part of their character. The electro- 

 chemical theory was called in aid, in addition to 

 the composition, because, distinguishing the ele- 

 ments of all compounds as electro-positive and 

 electro-negative, and giving to every element a 

 place in a series, and a place defined by the degree 

 of these relations, it seemed to afford a rigorous 

 and complete principle of arrangement. Accord- 

 ingly, Berzelius, in his First System, arranged 

 minerals acording to their electro-positjve element, 

 and the elements according to their electro-positive 

 rank ; and supposed that he had thus removed all 

 that was arbitrary and vague in the previous che- 

 mical systems of mineralogy. 



Though the attempt appeared so well justified by 

 the state of chemical science, and was so plausible in 

 its principle, it was not long before events showed that 

 there was some fallacy in these specious appearances- 

 In 1820, Mitscherlich discovered isomorphism : it 

 appeared that bodies containing very different elec- 

 tro-positive elements could not be distinguished from 

 each other; it was impossible, therefore, to put them 

 in distant portions of the classification ; the first 

 system of Berzelius crumbled to pieces. 



