168 Dr. Thomson on some of 
It appears from the preceding analysis, that 14-875 grains 
of the salt contain 
2 atoms sulphur - - 4 
1 atom soda - - - 4 
6 atoms water - - 6-75 
14-75 
The 0-125 wanting to make up the whole weight is equi- 
valent to an atom of hydrogen. If we consider it as combined 
with the two atoms sulphur, making an atom of bisulphuretted 
hydrogen, then the constituents of the salt will be as follows : 
1 atom bisulphuretted hydrogen - 4-125 
1 atom soda - 4 
6 atoms water - - - 6 - 75 
14-875 
It will appear immediately that these numbers exhibit 
the true composition of this hydrosulphuret. It is not, as 
Vauquelin supposed, a compound of sulphuretted hydrogen 
and soda, but of bisulphuretted hydrogen and soda. 
If we dissolve this salt in water and add to the solution 
sulphurous acid, as long as this acid continues to lose its 
smell, one half of the sulphur contained in the salt is thrown 
down, and the liquid will be found to contain nothing but a 
solution of hyposulphite of soda. If we concentrate the solu- 
tion sufficiently, it shoots into large transparent crystals of 
hyposulphite of soda. - 
These crystals are flat four-sided prisms, terminated by a 
bihedral summit. They have very much the taste of Glauber 
salt. When sulphuric acid is poured upon this salt, or still 
better, into an aqueous solution of it, sulphur is thrown down, 
