354 MM. Welter and Gay-Lussac on a new Acid [Nov. 



in the air, nor even in a vacuum dried by sulphuric acid. One 

 hundred parts of water, at the temperature of 4o\l°, dissolve 

 13*94 parts of this salt. The solution is not altered by chlorine. 

 The crystals decrepitate strongly. A moderate heat is sufficient 

 to decompose them ; water and 1 sulphurous acid is disengaged ; 

 and there remains a neutral sulphate of barytes : 100 parts of 

 the hyposulphate well dried in the air lost 20*903 by calcination; 

 and consequently left 70*097 of sulphate of barytes : 100 other 

 parts of the same salt mixed with the chlorate and carbonate of 

 potash, and heated to redness in a platinum crucible, gave, after 

 being precipitated by the chloride of barium, and properly 

 washed, 138*300 of sulphate of barytes. This number is not 

 exactly the double of 70-097 ; but as it is very difficult not to 

 lose a little of the sulphate of barytes during the washing, we 

 shall admit that the second number ought to contain the first 

 number exactly twice. On this supposition, the hyposulphate 

 of barytes may be considered as formed of one proportion of 

 barytes, one proportion of sulphuric acid, and one proportion of 

 sulphurous acid; and if we calculate the ratio of these elements, 

 taking 5*0 for sulphuric acid, 4*0 for sulphurous acid, and 9*7 

 for barytes, we find for 100 of the hyposulphate 70" 12 of sul- 

 phate of barytes, instead of 70*097. The quantity of water may 

 be determined from the difference between the weight of the 

 salt and that of the sulphate of barytes and sulphurous acid 

 extracted from it. We find from this analysis that the hype- 

 sulphate of barytes is composed of 



1 proportion of barytes 9*700 



1 proportion of sulphuric acid 5*009 



1 proportion sulphurous acid 4*000 



2 proportions of water. 2*264 



Or of 



1 proportion of barytes 9*700 



1 proportion of hyposulphurous acid . . 9*000 



2 proportions of water 2'2G4 



Consequently the hyposulphuric acid, which neutralizes one pro- 

 portion of base, is formed of 



2 proportions of sulphur 4*0 



5 proportions of oxygen 5*0 



and its equivalent number is 9*0 



Thus we have an acid which neutralizes the bases very well, 

 and whose bases remain in the state of neutral sulphates on 

 losing one proportion of sulphurous acid. It contains the same 

 proportion of sulphur as hyposulphurous acid, and 2-^- times as 

 much oxygen. These two acids miisi! constitute a particular 

 group among the acids of sulphur. Sulphurous and sulphuric 

 acid will form another. This distinction is riecessary, because 



