1819.] formed of Sulphur and Oxygen. 353 



sulphurous and sulphuric acid ; hut it differs from them exceed- 

 ingly in its properties and in its mode of composition, which 

 does not resemble that of any other acid. We shall distinguish 

 it provisionally by the name of liyposulphuric, from the analogy 

 of the hyposulphurous acid, in order to indicate that it contains 

 less oxygen than sulphuric acid, and more than sulphurous acid. 

 Its salts will take the name of hyposulphates. 



Hyposulphuric acid is formed when we pass sulphurous acid 

 gas into water, holding peroxide of manganese in suspension. 

 The combination takes place immediately, and we obtain a 

 solution perfectly neutral composed of sulphate and hyposul- 

 phate of manganese. The hyposulphate of barytes being soluble, 

 we decompose these salts by barytes, which is added in excess. 

 A current of carbonic acid gas is then passed through the liquid 

 to saturate the excess of barytes, and, by heating, to disengage 

 the carbonic acid, which retains in solution a small portion of 

 carbonate, we obtain the hyposulphate of barytes. To obtain 

 this salt quite pure, it is proper to crystallize it, because it may 

 contain lime, from which the peroxide of manganese is not 

 always free. By decomposing this salt with sulphuric acid to 

 perfect saturation, we obtain hyposulphuric acid in an uncom- 

 bined state. 



This acid has no smell even when as concentrated as possible. 

 Its taste is decidedly acid. It does not seem capable of assum- 

 ing the state of a permanently elastic fluid. When placed under 

 the vacuum of an air-pump along with sulphuric acid at the 

 temperature of 50°, it becomes concentrated without being sen- 

 sibly volatilized. When it reaches the specific gravity of 1*347, 

 it begins to be decomposed ; sulphurous acid is exhaled, and 

 sulphuric acid remains. When heated in a very diluted state, it 

 gives out pure water ; but by and by sulphurous acid is disen- 

 gaged, and sulphuric acid produced. The water-bath is suffi- 

 cient to produce this decomposition. While cold, it is not 

 altered by chlorine, concentrated nitric acid, or the red sulphate 

 of manganese. It saturates the different bases, and forms solu- 

 ble salts with barytes, strontian, lime, oxide of lead, and probably 

 with all the bases. It dissolves zinc with the disengagement of 

 hydrogen without being decomposed. It contains two propor- 

 tions of sulphur and five of oxygen, and a certain quantity of 

 water which appears essential to its existence when not united 

 to a base. It was by the analysis of the hyposulphate of barytes 

 that we were led to that of hyposulphuric acid. 



This salt forms brilliant crystals in four-sided prisms termi- 

 nated by a great number of faces. It undergoes no alteration 



- 



he employed lo procure chlorine, and he remarked, contrary lo the received opi- 

 nion, that there was formed a neutral bisulphite, which he conceived to contain 

 peroxide, as its base. lie mentioned this fact to me, and requested me to examine 

 it. We united together in my laboratory at the direction ilea poudrcs, to examine 

 the subject. — G.-I,. • 



Vol. XIV. N° V. Z 



