2 Biography of Berzelius. 



existence of dissimilar stages of saturation in the double salts 

 of silica, was less probable, especially as he had never met 

 with any similar phenomena in his investigations of the 

 double salts of other acids. Nevertheless, he subsequently 

 altered this view, after he had himself first prepared the re- 

 markable double salt of neutral carbonate of magnesia and 

 bicarbonate of potash. 



The salts of silicic acid, and indeed all true compounds oc- 

 curring in natural as well as artificially prepared salts, re- 

 ceived formulae which expressed their composition. But as 

 Berzelius was long doubtful how many atoms of oxygen he 

 should assume in silica, and even when he afterwards decided 

 for three atoms, did not regard this assumption as perfectly 

 certain, he introduced more simple formulae for siliceous com- 

 pounds, which he termed mineralogical, and distinguished 

 from the chemical formulae by the printers' type employed. 



The establishment of correct formulae, especially for sili- 

 ceous compounds, involved great difficulties since the composi- 

 tion of very few minerals was known with any degree of cer- 

 tainty. The first quantitative analyses of minerals were made 

 by Torbern Bergman, but according to such imperfect methods 

 that they scarcely indicated anything more than the qualita- 

 tive composition. After these came the analyses of Klaproth, 

 which compared with those of Bergman were a considerable 

 and encouraging advance, for he had not only employed 

 better methods of investigation, but also worked with much 

 greater accuracy. But even the analyses of Klaproth as well 

 as those of Vauquelin and others, who worked simultaneously 

 with him, when put to the test of definite chemical propor- 

 tions were not found to be unquestionable. It is true that 

 at first Berzelius could very often only propose a conjectural 

 formula for the composition of many minerals, and generally 

 only when he made some slight alterations in the results of 

 the then known analyses, in doing which, however, he always 

 proceeded with great caution. Afterwards these incorrect 

 analyses were replaced by correct ones, and indeed especially 

 by Berzelius himself and his pupils, who employed in their 

 analyses the most accurate methods proposed by him. 



Berzelius first arranged minerals according to their electro- 



