3-i8 HISTORY OF MINERALOGY, 



and supposed that lie Lad thus removed all that ^as hrbitrary and 

 vague in tlie previous chemical systems of mineralogy. 



Though the attempt appeared so well justified by the state of che 

 mical 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: by that 

 discovery it appeared that bodies containing very different electro- 

 positive elements could not be distinguished from each other ; it was 

 impossible, therefore, to put them in distant portions of the classifica- 

 tion ; and thus the first system of Berzelius crumbled to pieces. 



But Berzelius did not so easily resign his project. With the most 

 unhesitating confession of his first failure, but with undaunted courage, 

 he again girded himself to the task of rebuilding his edifice. Defeated 

 at the electro-positive position, he now resolved to make a stand at the 

 electro-negative element. In 1824, he published in the Transactions 

 of tLe Swedish Academy, a Memoir On the Alterations in the Chemi- 

 cal Mineral System, which necessarily follow from the Property 

 exhibited by Isomorphous Bodies, of replacing each other in f/icen 

 Proportions. The alteration was, in fact, an inversion of the system, 

 with an attempt still to preserve the electro-chemical principle of 

 arrangement. Thus, instead of arranging metallic minerals according 

 to the metal, under iron, copper, &c., all the sulplmrets were classed 

 together, all the oxides together, all the sulphates together, and so in 

 other respects. That such an order was a great improvement on the 

 preceding one, cannot be doubted ; but we shall see, I think, that as a 

 strict scientific system it was not successful. The discovery of isomor- 

 phism, however, naturally led to such attempts. Thus Gmelin also, in 

 1825, published a mineral system, 5 which, like that of Berzelius, 

 founded its leading distinctions on the electro-negative, or, as it was 

 sometimes termed, the formative element of bodies ; and, besides this, 

 took account of tLe numbers of atoms or proportions which appear in 

 the composition of the body ; distinguishing, for instance, Silicates, as 

 simple silicates, double silicates, and so on, to quintuple silicate (Pech- 

 steiii) and sextuple silicate (Perlstein). In like manner, NordenskiiiM 

 devised a system resting on the same bases, taking into account also 

 the crystalline form. In 1824, Beudant published his Trait e Elernen- 

 taire de Mineralogie, in which he professes to found his arrangement 

 on the electro-negative element, and on Ampere's circular arrange 



Zeitsch. der W.n. 1825, p. 435. 



