l66 
Dr. Thomson on some of 
a phial, gradually deliquesced into a brown liquid. Its alkaline 
properties were as powerful as those of a strong caustic 
potash ley : that is to say, it rendered cudbear paper purple, 
and dissolved the cuticle and nails of the fingers very 
speedily. When heated, it underwent the watery fusion, 
then became a solid salt, which caught fire and glowed or 
burnt like tinder for a considerable time with a very low 
yellow-coloured flame. 
This salt had been noticed by Vauquelin in 1802. He 
obtained it from the carbonate of soda manufactured by 
Payer and Bourlier, and described its characters under the 
name of hydrosulphuret of soda.* 
I dissolved 50 grains of these crystals in water, and added 
to the solution muriatic acid in sufficient quantity to saturate 
the soda, which I knew it, from previous trials, to contain. 
A smell of sulphuretted hydrogen was at first given out 
abundantly : this was soon followed by the odour of sulphu¬ 
rous acid, while at the same time sulphur was deposited. 
The solution being filtered and evaporated to dryness, left 
25*3 grains of common salt, equivalent to i3’49 grains of 
soda. 
50 grains of the salt being heated in a retort lost 29-2 
grains of their weight. The retort was blackened by the 
action of the sulphur on the oxide of lead in the flint glass. 
The liquid collected in the receiver weighed 25’4 grains. It 
contained sulphuretted hydrogen and a small quantity of the 
original salt. 
To determine the quantity of sulphur in this salt, 31*25 
grains of sulphate of copper (containing 10 grains of oxide of 
* Ann. de Chim. 41, 190. 
