22 BerzeUus on anew Mineral Body, [Jan. 



the borates and the carbonates ; yet boron and carbon have no 

 aaalogy with selenium, it is true that boron may be combined 

 with the alkahes ; but I do not know that any one has hitherto 

 produced a boruret of hydrogen or borurets analogous to the 

 metallic sulphurets and 'seleniurets. Every one knows that 

 carbon does'not combine with the alkalies, and in a very small 

 proportion with the metals ; and, finally, that carburetted hydro- 

 gen has not the hepatic taste and smell, nor possesses the proper- 

 ties of an acid. 



Selenium has no analogy, as far as its chemical characters are 

 concerned, with arsenic and phosphorus. It is obedient to the 

 reneral laws of the combination of oxidated bodies, from which 

 the tv.^o former deviate in so remarkable a degree. Their com- 

 binations with hydrogen, though possessing several properties of 

 the gases containing much hydrogen, are not hepatic, and do 

 net possess the properties of acids. We may say that arsenic is 

 to phosphorus what selenium is to sulphur ; but in fact there is 

 very little analogy between these two pair of bodies. 



12. Researches iiilo the State in which Selenium is found in the 



Mineral Kingdom. 



By the care of my friend M. Gahn, I received, during my 

 experiments, a portion both of the pyrites of Fahlun, employed 

 ill the manufacture of the sulphur, and of the impure sulphur 

 itself. 



The pyrites was partly pure and partly mixed with blende, 

 £;alena, chlorite, and several other foreign bodies. By roasting 

 either before the blow-pipe or on a furnace, it was impossible to 

 perceive any smell of horseradish. 



I dissolved 10 grammes of this pyrites in nitromuriatic acid. 

 The solution was precipitated by sulphuretted hydrogen gas, and 

 the precipitate was again dissolved in nitromuriatic acid. The 

 liquid was then saturated with potash, filtrated, and evaporated, 

 to dryness. The salt obtained was mixed with sal-ammoniac, 

 and exposed to a high temperature. After having dissolved the 

 saline mass, selenium remained ; but its quantity was so small 

 that it could not be weighed. 



The impure sulphur gave, by a similar treatment, about O'OOIS 

 of its weight of selenium. This quantity, small as it is, would 

 furnish a considerable annual quantity of selenium, did not the 

 other impurities, and particularly the arsenic, hinder it from 

 being employed. The purified sulphur furnished traces of sele- 

 nium scarcely perceptible. 



The experiments with the pyrites of Fahlun appeared to show 

 that the selenium is scattered through the whole substance of 

 the stone, although in a quantity infinitely small. However, as 

 St sometimes happens at Fahlun that the roasting of the copper 

 pyrites exhales a strong odour of horseradish, we may presume 

 that a mineral containing selenium occurs here and there in a. 



