Researches on the Salts of Selenious Acid. 



3 



PREPARATION OF SELENIOUS ACID FROM A SELENIFEROUS 



DEPOSIT. 



The material for the preparation of the acid was a deposit from the 

 sulphuric acid manufactory at Falun. For it I am indebted to the kindness 

 of the Director M:r A. Bohman, who obligingly placed large quantities at 

 my disposal. 



The deposit was a slippery mass of a strong red colour, moistened 

 throughout with sulphuric acid and, for the most part, composed of sulphate 

 of lead, sulphur and selenium [about 2.5 per cent.] Besides, I have found 

 in it smaller quantities of iron, copper, tin, antimony, arsenic, bismuth, cal- 

 cium, magnesium, aluminium and phosphoric acid. Washed and dried, it 

 formed a powder of grey colour with a reddish tint. 



Berzelius, as is known, discovered selenium in the residue from the 

 sulphuric acid manufactory of Gripsholm, which consumed sulphur from Falun. 

 His material was consequently taken from the same source, as that here em- 

 ployed. The question in what minerals selenium is to be found in the neigh- 

 bourhood of Falun, and what is the reason of its occurring in the leaden cham- 

 bers, is no more settled now, than at the time of Berzelius' first researches. 

 He found it, in minerals from Falun, only as a subordinate ingredient, for 

 instance in iron pyrites and galena and was but able to advance the hypothesis 

 that there, as at Skrikerum, it ought to be possible to find selenium as an 

 essential ingredient of a mineral. The only discovery that can be said to 

 indicate the existence of anything of that kind at Falun, has been made by Mr 

 Tholander 1 ) and appears, according to an analysis, to be composed of bismuth 

 with bismuth-glance and galena, containing about 1 per cent of selenium. 



For treating such a seleniferous deposit, as the above-mentioned, the 

 following methods have been suggested and adopted. 



Berzelius 2 ) treated it with nitro-muriatic acid, precipitated the solu- 

 tion with hydrosulphuric acid, dissolved once more the precipitate in aqua 

 regia, expelled the excess by heat, acted upon the residue with alkali, 

 heated first alone, then with sal-ammoniac, and at last selenium sublimated, 

 free from impurities previously present in it, of iron, zinc, copper, tin, ar- 

 senic, mercury and lead. A precisely similar proceeding is indicated by 

 Liebe 3 ) in i860, only with the difference that the heating with sal-ammo- 



') Geol. foren. i Stockholm forh. Bd. II N:o 3. 



2 ) Afliandlingar i Fys., Kemi och Miner. VI s. 50. 



3 ) Arch. Pharm. S. 150. [I860]. 



