HISTORICAL INTRODUCTION. 21 



compound bodies. He shows that when a me- 

 tallic proto-sulphuret is converted into a sul- 

 phate, the sulphate is always neutral ; that an 

 atom of sulphur is twice as heavy as an atom of 

 oxygen 5 and that when sulphite of barytes is 

 converted into sulphate, the sulphate is neutral, 

 there being no excess either of acid or base. 

 From these, and many other important facts, he 

 finally draws this conclusion : " In a compound 

 formed by the union of two oxides, the one 

 which (when decomposed by the galvanic bat- 

 tery) attaches itself to the positive pole (the 

 acid, for example,) contains 2, 3, 4, 5, &c. times 

 as much oxygen, as the one which attaches itself 

 to the negative pole, (the alkali, earth, or me- 

 tallic oxide). 5 ' Berzelius' Essay itself appeared 

 in the third volume of the Afhandtingar i Fysik, 

 Kemi och Mineralogie, printed at Stockholm in 

 1810, where it occupies 114 pages. A transla- 

 tion of it was inserted almost immediately, in Gil- 

 bert's Annalen der Physik, and in the Annales de 

 Chimie ; but no English translation of this most 

 important paper has ever been given to the 

 public. In 1815, Berzelius applied his views 

 to the mineral kingdom. His Essay was pub- 

 lished in the fourth volume of the Af hand- 

 lingar, and an English translation of it by Mr. 

 Black was soon after printed. And some 

 years after, Berzelius himself got a French 

 translation of it published in Paris. The fifth 



B3 



