397 
Mr Herschel on Hyposulphurous Acid. 
sulphate and acetate, would have done. The second portion receiv- 
ed successively into nitrates of silver and mercury, precipitated 
the metals copiously in the state of sulphurets, but produced 
no effect on solutions of copper, iron, zinc, he. The third had 
an acid, astringent and very bitter taste, When fresh filtered 
it was clear, but became milky on standing, depositing sulphur, 
and evolving sulphurous acid. A moderate exposure or a 
gentle heat effected its entire decomposition. The same results 
are obtained when dilute sulphuric acid is made to act on an 
excess of hyposulphite of baryta, suspended in a large quantity 
of water. 
These results confirm the opinion of Gay Lussac on the con- 
stitution of the hyposulphites, by separating their acid with all 
its characters, while they are unfavourable to the original idea 
of Berthollet, which makes them sulphurets of sulphites, or 
S -b I (S 2 O) -j- B j- as well as to the strange hypothesis 
since advanced by Ampere in the Annales de Chimie (1816), 
which regards them as sulphites of sulphurets, (S S O) -f- 
(B -f- S), making the alkaline quality of the base (B) survive its 
saturation with sulphur. 
The habitudes of oxide of silver in union with this acid are 
very peculiar. The strong afiinity between these bodies is 
shewn by the following facts, I poured hyposulphite of soda 
on newly precipitated oxide of silver; hyposulphite of silver 
was formed, and soda in a caustic state set at liberty, the only 
instance I believe yet known of the direct displacement of a 
fixed alkali by a metallic oxide, via Jiumidd. On the other 
hand, hyposulphurous acid, newly disengaged from the hypo- 
sulphite of baryta, readily dissolved and decomposed muriate of 
silver, forming a sweet solution, from which alcohol separated 
the metal in the state of hyposulphite. Thus, the affinity be- 
tween this acid and base, unassisted hy any double decomposi- 
tion., is such as to form an exception to all the ordinary rules of 
chemical union. 
The neutral hyposulphites readily dissolve and decompose 
the chloruret, carbonate, phosphate, borate, oxalate and sul- 
phite of silver, the arseniate less readily, and the ioduret very 
sparingly. The sulphate is converted into sulphuret, and free 
VOL. T. NO. % OCTOBER 1819. I) d 
