1819.] extracted from Pyrites at Fahlun. 261 



Seleniuret of Ammonia. — Ammonia does not dissolve selenium 

 either in the state of gas, or in the liquid ; but if we distil muriate 

 of ammonia with seleniuret of lime, we obtain in the receiver a 

 red liquid, having an extremely hepatic taste, which may be 

 mixed with a certain quantity of water without undergoing 

 decomposition, and which, when left in the open air, lets go its 

 ammonia, and leaves the selenium in the form of a grey metallic, 

 pellicle. If it be diluted with a great quantity of water, it is 

 decomposed, and has a yellow opalescent colour when viewed by 

 transmitted light ; but a cinnabar-red colour by reflected light. 

 The selenium remains long suspended in it. During the prepa- 

 ration of that compound, a portion is decomposed ; the ammonia 

 is disengaged in the form of gas, and selenium sublimes. Hence 

 it follows that this combination is very weak, and is partly 

 decomposed during its preparation. The matter remaining in 

 the retort after the distillation of seleniuret of ammonia is a mix- 

 ture of muriate, seleniate, and hydroseleniuret of lime : the last 

 two were formed by the decomposition of a portion of the water 

 of crystallization of the muriate of ammonia. If we dissolve 

 them in weak muriatic acid, the liquid acquires the odour of 

 seleniuretted hydrogen, becomes muddy and red when exposed 

 to the air, and deposits selenium. 



Seleniuret of Lime. — If we mix selenium in powder with lime, 

 and then expose the mixture to a strong but not a red heat, the 

 two substances combine and form a cohesive black mass, without 

 taste and smell, and which does not dissolve in water. It yields 

 a reddish-brown powder, and on adding an acid, it is decom- 

 posed, leaving the selenium in the state of very bulky red flocks. 

 The swelled state of the selenium shows that the mass was a 

 true compound, and not merely lime mechanically mixed with 

 melted selenium. 



If we expose this black seleniuret to a red heat, it lets go a 

 portion of its selenium, and its colour becomes lighter. It yields 

 in that state a flesh-coloured powder, but it is equally insoluble 

 and tasteless, as the black seleniuret. We may obtain the 

 same compound by mixing a solution of muriate of lime with that 

 of seleniuret of potash. A seleniuret of lime is formed which 

 precipitates in the form of a red powder. 



I obtained the seleniuret of lime crystallized by leaving a 

 solution of hydroseleniuret of lime in an imperfectly stopped 

 vessel, in which it could be slowly oxidized. The liquid by little 

 and little lost its colour, and deposited seleniuret of* lime at its 

 surface. At the same time, brown and opaque needles were 

 attached to the sides of the vessel, united together three and 

 three, forming angles of 120°. In some of the groups, there 

 were four or five little crystals. Under the microscope they 

 appeared to be four-sided prisms, with truncated summits. The 

 liquid still contained an excess of lime. 



