1820.] Physical Science during the Year 1819. 21 



edition of my System of Chemistry, that the true composition of 

 sulphuric acid is 



Sulphur 100 



Oxygen 160 



or 1 atom of sulphur = 2 + 3 atoms oxygen = 3, 



We are now acquainted with four acid combinations of sulphur 

 and oxygen ; namely, 



Sulphur. Oxygeu. 



1 . Hyposulphurous acid composed of. . . 1 atom + 1 atom 



2. Sulphurous acid 1 +2 



3. Sulphuric acid 1 +3 



4. Hyposulphuric acid 2 +5 



or this last acid may be considered as a compound of one atom, 

 of sulphurous acid and one atom of sulphuric acid. 



Hyposulphurous acid makes its appearance in many cases not 

 hitherto suspected. The knowledge of its properties is essential 

 towards the knowledge of the phenomena which take place when 

 the hydrosulphurets and hydroguretted sulphurets undergo spon- 

 taneous changes from exposure to the atmosphere. These 

 changes will now admit of an easy explanation, since we are 

 acquainted with the nature and properties of this peculiar acid, 

 and of its salts. 



Hyposulphuric acid has been only recently discovered by 

 Gay-Lussac and Welter. They obtained it by passing a current 

 of sulphurous gas through water, in which the black oxide of 

 manganese was suspended. Sulphate and hyposulphates of man- 

 ganese were formed. These salts were decomposed by means of 

 carbonate of barytes. Nothing remained in solution but hypo- 

 sulphate of barytes. It was crystallized, redissolved in water, 

 and the barytes precipitated by the cautious addition of sulphuric 

 acid. It appears from the experiments of these chemists that 

 hyposulphuric acid is a compound of one atom of sulphuric and 

 one atom of sulphurous acid. It may be concentrated to a cer- 

 tain point, but beyond that, if the concentration be urged, 

 sulphurous acid escapes, and nothing remains but sulphuric 

 acid. All the salts which this curious acid forms with bases^ 

 appear to be soluble. (See Annals of Philosophi/, xiv. 352.) 



I translated and published in the Annals of Philosophi/, xiv. 

 37, a paper by Sertiirner on the action of sulphuric acid on 

 alcohol. He concludes from his experiments, that a combina- 

 tion takes place between these two substances, and that three 

 new acids may be formed to which he has given the names of 

 protoinothionic, deutoinothionic, and tritoinothionir acids. These 

 acids, he assures us, are capable of combining with the different 

 bases, and of forming each a peculiar genus of salts. He assures 

 us that this capacity of uniting is not confined to sulphuric acid 



