24 
Mr Herschel on the Hy'pomt'phurous Acid, 
Lime, 45.04 
Bisulpnuretted > gg (—^5.37 sulplmr-f 0.84 hydrogen) 
hydrogen, j 
, Water, 28.75 
100.00 
One half the sulphur contained in the crystals is therefore 
12.68 ; and, as this coincides very nearly with the 12.44 dis- 
engaged by muriatic acid in the first experiment, we are autho- 
rised to conclude, that the other half would precisely saturate 
the hydrogen present, if in the state of sulphuretted hydrogen. 
When sulphurous acid is ground with these crystals in a mor- 
tar, its smell disappears ; and when filtered, it is found to be a 
solution of hyposulphite of lime. The same result is obtained 
when a current of sulphurous acid gas is passed through any 
lixivium formed by boiling lime with sulphur, or through the 
hydrosulphuret. The whole of the sulphurous acid is converted 
into hyposulphurous ; and when the latter method is employed, 
pure sulphur, unmixed with an atom of sulphite of lime, is pre- 
cipitated, while the hyposulphite remains in solution. 
When this solution is boiled down to a certain degree of con- 
centration, it begins to be rapidly decomposed, and sulphur and 
sulphite of lime separate in such abundance, that nothing is 
gained by continuing the ebullition. (These may be again unit- 
ed into hyposulphite by digestion in a large quantity of water.) 
If we would obtain the salt in crystals, the solution must be far- 
ther evaporated at a temperature not exceeding 130®, or at most 
140° F. Filtered while hot, it then yields, on cooling, large 
and exceedingly beautiful crystals, which affect a great varie- 
ty of very complicated forms. The most common, however, is 
the hexangular prism, whose sides are inclined to each other at 
angles of 141® 39', 110® 45', and 107® 36', and two of whose 
sides are usually much smaller than the others. These crystals 
have a natural joint or cleavage, parallel to the axis, and the 
two smaller sides (or dividing the larger angle of the prism) as 
perfect and well defined as that of any crystallized mineral ; be- 
sides which, indications of natural joints, parallel to the two 
other sides, may be detected. They are doubly refractive, the 
indices for the two refractions being respectively about 1.583 
