334 Biographical Account of [Nov. 



azote, or of oxide of gold and azote. But we have no proof 

 that this is really its composition. 



13. On Platina. — This dissertation was published in 1777, 

 and is chiefly valuable as explaining the effects of the alkalies 

 when dropped into a solution of platinum. It was Bergman that 

 first showed that sal-ammoniac precipitates platinum by forming 

 with it a triple salt which is but little soluble in water. Potash 

 produces a similar effect ; but soda and lime- do not form triple 

 salts, but precipitate, according to him, the metal in the state 

 of an. oxide. 



14. On the White Ores of Iron. — This paper, first published 

 in 1774, contains the first account of the properties of the metal 

 called manganese. These properties were partly detected by 

 Bergman, partly by Scheele, and partly by Gahn. It was Gahn 

 that first obtained manganese in the metallic state. It would 

 be needless to give the substance of this elaborate and valuable 

 paper ; because we are now possessed of more accurate means 

 of analysis ; and the properties of manganese are known with 

 greater precision than they were when Bergman wrote. Berg- 

 man's method of separating iron and manganese from each 

 other by solution in nitric acid and calcination was used till 

 Vauquelin substituted another, which, however, does not suc- 

 ceed better. 



15. On Nickel. — This paper was published in 1775. It con- 

 tains an elaborate set of experiments to obtain nickel in a state 

 of purity. These experiments were all made in the dry way ; 

 and were not perfectly successful. But our author succeeded 

 in establishing the peculiar nature of this metal by showing that 

 its properties became more and more peculiar the more com- 

 pletely it is freed from foreign bodies. 



16. On Arsenic. — This paper, originally published in 1777, 

 contains the fullest and best account of the properties of arsenic 

 which has yet appeared. It contains, indeed, certain mistakes 

 and erroneous deductions, which flowed unavoidably from the 

 state of the science in 1777. Except the correction of these 

 mistakes, and more exact numeral results, the chemical know- 

 ledge of arsenic has advanced but little since the days of 

 Bergman. 



17. On the Ores of Zinc. — This dissertation was published in 



1779, and contains an analytical examination of all the ores of 

 zinc which were then known. He succeeded in pointing out 

 the constituents of all these ores with sufficient accuracy ; 

 though his methods were not sufficiently precise to enable him 

 to obtain the accurate proportions of each. 



18. On Metallic Precipitates. — This paper, first published in 



1780, is one of the most elaborate productions which Bergman 

 has left us. It may be considered as the first attempt to inves- 

 tigate the nature of the metallic oxides, and to point out the 

 state in which the different metals are precipitated by various 



