102 Berzelius on a new Mineral Body, [Ave 



probable that the gas being absorbed by the humidity of the 

 internal membrane, and decomposed by oxygen of the air, the 

 selenium formed an injurious incrustation on the living parts, 

 •which the animal economy endeavours to get rid of. Hence the 

 symptoms. 



To determine the composition of seleniuretted hydrogen gas, 

 I passed a current of it into a solution of acetate of silver, which 

 had been ju&t deprived of air by a long continued boiling. The 

 black precipitate thus obtained, being washed and dried in a 

 temperature above that of boiling water, weighed 1-888 gramme. 

 I dissolved it in pure nitric acid, and poured the solution while 

 boiling hot into a heated mixture of muriatic acid and water. 

 The precipitate of muriate of silver being washed, dried, and 

 fused, weighed 1-844 gramme, equivalent to T389 gr. of silver. 

 The seleniuret of silver of consequence contained 0499 of sele- 

 nium ; but 1-389 of silver had lost 0-1028 of oxygen when 

 reduced from the state of an oxide. The quantity of hydrogen 

 necessary for this reduction is 0*01363. This quantity of course 

 was combined with the 0-499 of selenium. This quantity of 

 selenium would have required 0-2015 of oxygen to be acidified ; 

 but this quantity of oxygen is almost exactly twice that which 

 the silver had lost. 



It follows that an atom of silver had been combined with two 

 atoms of selenium ; and as the oxide of silver is supposed to 

 contain two atoms of oxygen, these two atoms must have been 

 combined with four atoms of hydrogen. Seleniuretted hydrogen 

 gas then is composed of two atoms of hydrogen and one atom of 

 selenium. This is both analogous to the composition of sulphu- 

 retted hydrogen and of water. 



Seleniuretted hydrogen gas and seleniuret of hydrogen then 

 are composed by weight of 



Selenium 97-4 495-91 = 1 selenium 



Hydrogen 2-6 13-27 = 2 hydrogen 



100-Q 



6. Selenium rvith Sulphur and Phosphorus. 



Sulphuret of Selenium. — Sulphur and selenium may be mixed 

 together while liquid in every proportion, just as is the case with 

 sulphur and phosphorus. One per cent, of sulphur in selenium 

 renders it more fusible, more red, and more transparent ; but its 

 fine ruby colour becomes tarnished. While this mixture remains 

 very hot, it is black, opaque, and clammy. While cooling, it 

 becomes liquid, dark red, and transparent, and it preserves its 

 colour and its transparency after becoming solid. It is well 

 known that sulphur likewise is black and clammy at a high 

 temperature, and that by lowering the temperature, it becomes 

 liquid and transparent. One part of selenium may be mixed, 



