354 SULPHURETS. 



oxygen that existed, both in the oxidized base and in the sulphuric 

 acid ; and when hydrogen is employed, the water produced, accounts 

 in the same manner, for the whole of the oxygen, and there is in either 

 case, no loss of sulphur, as it all remains combined with the metallic 

 base forming a true metallic sulphuret. 



When the sulphurets of the metallic bases of the alkaline sub- 

 stances are dissolved in water, they pass at once, to the condition of 

 hydro-sulphurets and sulphuretted hydro-sulphurets. The decom- 

 position of the water appears to be the means of effecting these 

 changes ; its oxygen causes the metal to pass to the state of oxide, and 

 its hydrogen with a part of the sulphur forms sulphuretted or bi-sul- 

 phuretted hydrogen ; some of the acids of sulphur are also formed. 

 When a sulphuret is obtained by the decomposition of sulphate of 

 baryta by charcoal and heat, and subsequent addition of boiling wa- 

 ter, there is produced, from a strong solution, a very copious and 

 sudden deposition of white crystalline plates of hydro-sulphuret of 

 baryta, while a part of the fluid appears to remain in the condition of 

 sulphuretted hydro-sulphuret or bi-hydro-sulphuret of baryta. Sul- 

 phurous acid or hypo-sulphurous acid is also produced, and combin- 

 ing with a portion of the oxidized base contributes to expel more sul- 

 phuretted hydrogen. 



In concluding this rather complicated subject, it may be well to 

 call to the recollection of the learner, that the following are its great 

 divisions. 



1 . Sulphuretted and U-sulphurettcd hydrogen, containing sulphur 

 dissolved in hydrogen ; one proportion in the former, and two in the 

 latter. 



2. Hydro-sulphurets, consisting of sulphuretted hydrogen, and an 

 oxidized metallic base* of an alkaline substance ; in other words, of 

 an alkali or an earth. f 



3. Sulphuretted hydro-sulphurets, consisting of bi-sulphuretted hy- 

 drogen, and oxidized metallic bases, viz. alkalies and earths ; pro- 

 bably containing also variable proportions of sulphur dissolved, besides 

 what is united to the hydrogen. 



4. Sulphurets of the alkalies and earths, formed below ignition. 



5. Sulphurets of metallic bases, formed above ignition and con- 

 taining no sulphuretted hydrogen, nor any uncombined sulphur. 



* Ammonia being always exceptecl as having a different constitution, but still, it 

 forms a true hydro-sulphuret, and one of the most useful, 

 t The common metals are not here brought into view. 



