16 Berzelius on a new Mineral Body, [Jan. 



of my suggestion : " We consider this idea might be adopted 

 with propriety, and probably with effect." 



I must confess, without presuming too much, that I look upon 

 the favourable opinions of such men as I have named as no 

 common sanction to the measure I have proposed ; and I have 

 only once more to express a hope that it will undergo the test 

 of experiment upon a scale that will either confirm its utihty, or 

 disprove its efficacy. 1 have the honour to be. Sir, 



Your very obedient servant, 



J. M. Bartlett. 



Article III. 



Researches on a new Mineral Body found in the Sulphur extracted 

 foom Pyrites at Fahln/i. By J. Berzelius. 



{Concluded from vol. xiv. p. 427.) 



10. Co7nhination of Seleniuret of Hydrogen with the Bases of the 



Hydroselemurets. 



The seleniuret of hydrogen possesses the same properties as 

 the sulphuret and telluret of hydrogen ; it changes the blue 

 colour of litmus to red ; unites as an acid with those bases 

 whose radicals have a stronger affinity for oxygen than that of 

 hydrogen ; and reduces the others to the state of metallic sele- 

 niurets. The soluble hydroseleniurets have the taste, and like- 

 wise to a certain degree the smell, of liver of sulphur, and cannot 

 by these characters be distinguished from the hydrosulphurets ; 

 but they have a deep red or orange colour, and in this respect 

 approach the hydrotellurets. But I must observe that the 

 colour of these last is much more beautiful, and has a tinge of 

 purple, like red wine ; while that of the hydroseleniurets has a 

 tint of yellow, and approaches the colour of strong ale. The 

 liydroseleniurets produce spots upon the skin, which are black, 

 brown, or yellow, according to the intensity of the solution, and 

 •which cannot be removed by water. 



I cannot determine whether this colour belongs to the hydro- 

 seleniurets as essentially as it does to the hydrotellurets, or 

 whether it be owing to an excess of selenium dissolved by the 

 hydroseleniuret. I melted selenium with an excess of potassium; 

 the combination was attended with an explosion by which a 

 great portion of the mass was lost ; but what remained gave an 

 orange-red colour, though there was a disengagement of hydrogen 

 during its solution. This observation seems to prove that at 

 least the alkaline hydroseleniurets are coloured. But I ought to 

 observe that I did not repeat this experiment, though it iu some 

 measure failed. 



