M. Gay-Lussac's Observations on some Sulphurets. 113 



name of bi-hydrosulphate, because I found that it contained 

 two atoms of acid. (Ann. de Ch. et de Ph. vol. xiv. p. 263.) In 

 giving to the alkaline solution, to that of potash, for example, 

 only half as much acid as it can saturate, it is possible either 

 that a simple hydrosulphate or sulphuret will be produced, 

 or that one half of the alkali forms a hydrosulphate of the sul- 

 phuret of potassium, while the other half of it remains free. 

 It would be very difficult to determine precisely what hap- 

 pens ; but, happily, that is quite immaterial in practice. 



In paying attention to the analogy which exists between the 

 carbonic and hydrosulphuric acids, and to their property of 

 separating one another from their combinations, one would 

 expect heat to expel one half of the acid of the bi-hydrosul- 

 phates, since it produces that effect on the bi-carbonates. But 

 this is not the case : the bi-hydrosulphates sustain a very high 

 temperature without losing their acid. This result seems to 

 confirm the opinion that the hydrosulphate of the sulphuret 

 of potassium dissolves in water without decomposing it, and 

 that it acts with this liquid like the chlorurets and iodurets ; 

 but one may admit that it is decomposed without inconveni- 

 ence. 



On heating the carbonate of potash in an excess of hydro- 

 sulphuric acid, M. Berzelius has obtained a compound formed 

 of an atom of sulphuret of potassium, and an atom of hydro- 

 sulphuric acid. This result might have been easily foreseen, 

 by remembering that hydrosulphuric acid in excess expels 

 carbonic acid, and converts potash into sulphuret of potassium. 

 The circumstances are then the same as where potassium is 

 heated in hydrosulphuric acid. 



M. Thenard has observed, that on heating a solution of the 

 hydrosulphate of potash with sulphur, (Ann. de Chim. vol. 

 lxxxviii. p. 132,) there is a disengagement of much hydrosul- 

 phuric acid ; and M. Berzelius has proved, that when we take 

 the hydrosulphate of the sulphuret of potassium, or, what 

 amounts to the same thing, the bi-hydrosulphate of potash, 

 the sulphur separates one atom of hydrosulphuric acid, and 

 four atoms of sulphur are dissolved. Hence the compound 

 is a sulphuret, with five atoms of sulphur, exactly similar to 

 that which is obtained when potash is heated with an excess 



vol. v. NO. I. JULY 1826. it 



