Mr Herschel mi tlie Ifypo^ulphurous Ackl 1$ 
I shall now proceed to describe some other compounds of the 
hyposulphurous acid. 
Hyposulphite of Potash. — This salt is readily prepared either 
by precipitating that of lime by the carbonated alkali, or imme- 
diately decomposing hydrosulphuret or hydroguretted sulphuret 
of potash by sulphurous acid, and evaporating to a pellicle. It 
then crystallizes into a confused mass of spiculae. It has a 
penetrating taste like nitre, succeeded by bitterness, and is very 
deliquescent, the deliquiated salt crystallizing in fine needles by 
a slight diminution of temperature. By the action of a gradu- 
ated heat, it boils down to a dry white mass, then takes fire, 
and burns much like a piece of tinder, but with a weak blue 
flame. It dissolves muriate of silver, even when very dilute, 
with great readiness. This salt is formed when the hydrogu- 
retted sulphuret of potash is decomposed by atmospheric expo^ 
sure, though Dr Thomson concludes, from his own experience, 
that it is only the sulphate which is so produced ; probably he 
tested his liquid with solutions of lead and baryta, which in this 
case are ambiguous. 
Hyposulphite of Soda — may be formed in precisely the same 
manner. It crystallizes on cooling, when evaporated to a sy- 
rup, in silky tufts radiating from centres, which at length extend 
through the whole liquid, and become almost solid. By the ac- 
tion of sulphuric acid in vacuo^ it effloresces, but in the open air 
is extremely deliquescent. Its taste is intensely bitter and 
nauseous. Heated, it first undergoes the watery fusion, then 
dries into a white mass, and at length takes fire, burning with a 
vivid deflagration, and a bright yellow flame. It is totally in- 
soluble in alcohol of 0.82344, which precipitates it from its so- 
lutions in a thick syrup. Muriate of silver, newly precipitated, 
dissolves in this salt, when in a somewhat concentrated solution, 
in large quantity, and almost as readily as sugar in water. 
Hyposulphite of Ammonia. — This salt is not easily procured 
in regular crystals. When much concentrated it cools into a 
confused pappy mass of very minute spiculge. Its taste is bit- 
ingly pungent, succeeded by a disgusting bitterness. Heated, 
it burns with a weak flame, and evaporates entirely. It does 
not appear to possess any remarkable properties. I made some 
attempts to analyse it, but the difficulty of procuring it in a de- 
