194 HYPOSULPHITE AND TRITHIONATE OF POTASH. 
employed. I found that none forms in this case, and never- 
theless there is absorption of sulphurous acid. MM. Gelis 
and Fordos have, however, analysed this reaction, and have 
been led to the following equation: — 
2(S 2 S 2 KO) + 3(SO) = S 8 O 5 KO + S 4 O 5 KO. 
The tetrathionate can be removed from the mother-ley 
from which the trithionate of potash was deposited. It is 
a white salt, not stable, but which keeps well enough in 
contact with the air when in the state of crystals and dry. 
When the absorption of sulphurous acid by the hyposul- 
phite of potash has determined the precipitation of a certain 
quantity of trithionate and of the tetrathionate of potash, 
some sulphate is found in the liquor. I have observed it 
form when access of air has been prevented ; for when a 
recently prepared solution of sulphurous acid in boiled dis- 
tilled water is passed under a bell-glass over mercury, and 
then a sufficient quantity of crystallized hyposulphite free 
from sulphate introduced, the sulphurous acid will be found 
to be completely absorbed after four-and-twenty hours, and 
the liquid forms a precipitate with chloride of barium, 
which does not dissolve entirely in dilute hydrochloric 
acid. 
Chemical Gazette, from Jinn, de Chim. et de Phys, 
