240 
MISCELLANY. 
perature that it could not melt, and but only slightly concrete. Du- 
ring the absorption of the sulphurous acid a strong developement of 
heat takes place ; and the pulverulent sulphuret of sodium becomes 
moist. These phenomena can be easily noticed if the sulphuret be 
placed in a glass tube, and the sulphurous acid be allowed to enter 
from beneath. At this stage no odour can be perceived at the upper 
opening of the tube, but as soon as the heating and moistening of the 
sulphuret have arrived at the upper end of the tube, sulphuretted hy- 
drogen gas begins to be developed, and sulphur to sublime on the 
sides of the tube. If the experiment be now interrupted, hyposul- 
phite of soda, containing carbon and some sulphuret of sodium, is 
found in the tube. This forms with water a pale yellow-coloured solu- 
tion; but if the sulphurous acid be allowed to pass as long as the 
sulphuretted hydrogen is detected, and until nothing but the excess of 
sulphurous acid is perceived, the product gives, when mixed with 
water, a colourless solution, which is free from sulphuret of sodium, 
and, therefore, quickly changes, on the admission of air, into sulphite 
and sulphate of soda. 
The sulphuret of sodium gains about 70 per cent, in weight (the 
water included.) The whole experiment lasts, when small quantities 
of sulphuret are used, scarcely a quarter of an hour, and from the car- 
bonaceous crude mass, crystallized hyposulphite of soda can be easily 
obtained. 
The facility with which solid hydrous sulphuret of sodium (hydro- 
sulphuret of soda) is converted, by means of sulphurous acid, into 
hyposulphite of soda, affords, therefore, a simple and cheap means of 
procuring this salt, which has latterly acquired some importance for 
Daguerreotyping and in the manufacture of paper. 
With regard to this process, it is particularly to be observed, that 
the transmission of the sulphurous acid into the powdered sulphuret of 
sodium must be stopped before the developement of sulphuretted 
hydrogen gas has ceased, in order to obtain hyposulphite of soda, con- 
taining some sulphuret of sodium, and consequently permanent in the 
air. — Pharm. Jour, from Buck. Reper. 
