SULPHURETTED HYDRO-SULPHURETS. 351 



3. According to Proust, a pure liquid sulphuret, without sulphuret- 

 ted hydrogen, may be formed, by withdrawing the latter by red ox- 

 ide of mercury.* 



SULPHURETTED HYDRO-SULPHURET OF MAGNESIA. 



By processes similar to those pointed out above, magnesia gives 

 but feeble indications of combining with sulphur, &c., and is the last 

 of the earths that gives any. 



Remarks. The elaborate researches of Berthollet, (1798,) for- 

 merly led us to suppose, that when a base is boiled with sufficient 

 sulphur, a fluid sulphuret was produced, which decomposed water, 

 and generated sulphuretted hydrogen, part of which was exhaled, 

 thus producing the peculiar odor of these preparations, and that the 

 remainder of this gas combined with the sulphuret, and formed what 

 was called hydrogenized sulphuret ; and it was thought to be a suf- 

 ficient proof of the truth of this opinion, that an acid decomposed the 

 preparation, evolving sulphuretted hydrogen and precipitating sulphur 

 abundantly, both of which facts were supposed to arise from the acid 

 seizing the base to form a salt. 



More recently, we are taught, that bi-sulphuretted hydrogen is gen- 

 erated in these cases, and that the excess of sulphur is contained in 

 that mode of combination. But I think this cannot be all that hap- 

 pens ; for there is great variety in the quantity of sulphuretted hydro- 

 gen, which acids evolve, and of sulphur which they precipitate from 

 these preparations. Sometimes, although sulphur is abundantly pre- 

 cipitated, very little gas makes its escape, and at other times it is 

 very abundant. I am persuaded that there is often much sulphur in 

 solution, which is simply dissolved by the entire compound, and is 

 not merely combined with the hydrogen in the form of sulphuretted 

 or bi-sulphuretted hydrogen'. My experience would lead me to ac- 

 cord with the following opinion of Dr. Ure.f 



1. Sulphuretted hydrogen, sulphur and the alkalies have the pro- 

 perty of forming very variable triple combinations. 



2. All these combinations contain less sulphuretted hydrogen than 

 the hydro-sulphurets ; and 



3. The quantity of sulphuretted hydrogen is inversely as the sul- 

 phur they contain, and reciprocally. 



SULPHURETS. 



I. Sulphurets of alkalies and alkaline earths. 



Remarks. Until within a few years, it was supposed that the fu- 

 sion of dry sulphur with the fixed alkalies and alkaline earths, produ- 

 ced a true sulphuret of the alkaline body, and it is still by no means 

 certain that, under particular circumstances, this is not the fact. It is 

 the opinion of Gay Lussac, that a true sulphuret of an oxide is form- 

 ed, provided the temperature is kept below ignition. "A une tem- 



* Aikin's Diet. Vol. II, p. 363. t Diet. 2d Ed. p. 756. 



