the compounds of chromium. 165 
this soluble portion was in the state of bihydrosulphuret of 
chromium. 
The residual liquid being evaporated to dryness left a 
deliquescent salt, possessing the following properties. Its 
taste was strongly alkaline, and it acted powerfully on cudbear 
paper, giving it a deep purple colour, as alkalies always do. 
Muriate of barytes dropt into the aqueous solution of the salt 
threw down a white precipitate, which was re-dissolved by 
adding a few drops of nitric acid. Acetate of lead occasioned 
a white precipitate. Sulphuric acid occasioned an effervescence, 
sulphurous acid was driven off, and abundance of sulphur was 
thrown down. These properties leave no doubt that the salt 
was a hyposulphite of potash. 
Thus it appears, that when a current of sulphuretted hydro- 
gen gas is passed for a sufficient time through a solution of 
chromate of potash, the whole chromic acid is converted into 
hydrosulphuret of chromium, while the potash becomes hypo- 
sulphite of potash. Before the rationale of these decompo- 
sitions, and new combinations can be given, it will be necessary 
to make the reader acquainted with the true composition of 
the hyposulphurous acid of Mr. Herschel, which is the kind 
of acid formed in the process just described. 
During the summer of 1825, which was remarkably hot 
and dry, there were formed in the soda leys of Mr. Charles 
Tennant, of Glasgow, numerous octahedral crystals possess- 
ing the following properties. 
The crystals seemed to be regular octahedrons, though 
they did not admit of accurate measurement. The taste of the 
salt was very hot, bitter, and sulphureous. It was not altered 
by twenty-four hours exposure to the air ; but when kept in 
