M. Berzelius on Vanadium. 329 



retted. Nevertheless, there are several modes of obtaining 

 sulphurets of vanadium; hitherto, only two have been formed, 

 proportional to the oxide and vanadic acid. 



I. Sulphuret of Vanadium. — This is obtained in the dry way 

 by exposing suboxide of vanadium to a current of sulphuretted 

 hydrogen at a red heaL Water, hydrogen, and even sulphur 

 are disengaged, and the vanadium is slowly converted into a 

 sulphuret. This sulphuret is black ; it becomes compact by 

 pressure; when burnished it has not a metallic lustre. Heated 

 ill platina foil, it burns with a blue flame, and leaves upon the 

 platina a circular pellicle, which is translucent, blue at the cir- 

 cumference and purple nearer the sulphuret. Water does not 

 remove this pellicle, but it disappears at a red heat, leaving 

 minute drops of vanadic acid. In this state sulphuret of va- 

 nadium is entirely insoluble both in sulphuric and muriatic 

 acids, and in the caustic alkalies. Nitric acid converts it into 

 sulphate of vanadium. 



The salts of vanadium are not decomposed by sulphuretted 

 hydrogen, but the hydrate and the salts of vanadium are con- 

 verted by the hydrosulphurets into sulpho-vanadates, which 

 dissolve in water; the solution has a rich purple colour. Acids 

 poured into these solutions occasion a brown precipitate, which 

 soon subsides and tlien appears black; it is the sulphuret of 

 vanadium : it may be washed and dried without undergoing 

 any alteration ; it dissolves with a purple colour in the alkaline 

 hydro-sulphurets. The alkaline carbonates also dissolve it 

 wlien l)oiling, but the colour of the solution is brownish yel- 

 low. The sulphuric and muriatic acids do not decompose it, 

 although the liquid from which it has been precipitiited re- 

 tains a bluish tint, in consequence of the decomposition of a 

 small quantity of nascent sulphuret. It is composed of 68*023 

 parts of vanadium, and 31*977 parts of sulphur. 



2. Supersulj)huret of Vanadium. — The affinity of sulphur for 

 vanadium is so weak, that when a current of sulphuretted hy- 

 drogen is passed into an aqueous solution of vanadic acid, the 

 precipitate is merely oxide of vanadium intimately mixed with 

 sulphur, from wiiich the acids separate the oxide without dis- 

 engaging sulphuretted hydrogen, and leave the sulphur. To 

 obtain tlie supersulphuret of vanadium, vanadic acid must be 

 dissolvetl in an alkaline hydro-sulphuret, or the solution of a 

 neutral vanadate of an alkali must be decomposed by sul- 

 jjhuretted hydrogen, and the suli)huret must be alterwards 

 precipitated by siil{)huric or muriatic acid. The colour of the 

 pncipitate is brown, but much less deep than that of (he pre- 

 ceding sulphuret; and there is this peculiar circumstance at- 

 tending it, that at the time of the addition of the aciil it de- 

 N.S. Vol. 10. No. 59. Nov. 1831. 2 U composes 



