Chemistry. xiv 
after it has ceased to give out air bubbles; then reduce the 
fused mass to powder, and pour hot water on it; filter the so- 
lution and drop into it caustic potash till all the iron which it 
contains is precipitated ; filter the liquid and concentrate it suf- 
ficiently by evaporation. The sulpho-chyazic of potash is ob- 
tained in crystals. This salt is white, deliquesces in the air, and 
is very soluble in alcohol. When a solution of this salt is dissolved 
in water and mixed with sulphuric acid, it yields, when distilled, 
water, holding pure sulpho-chyazic acid in solution. This liquid 
is colourless. I find that when kept it undergoes spontaneous 
decomposition. It ought, according to Vogel, to be kept in 
small phials quite filled with it. When newly prepared it has a 
peculiar pungent smell, reddens vegetable blues, and has an 
acid taste. It does not precipitate barytes water, and the pre- 
cipitate which it occasions in acetate of lead is soluble in cold 
water. 
Grotthuss made a very ingenious set of experiments to deter- 
mine the composition of this acid. According to him the con- 
stituents are as follows: 
3 atoms sulphur ........ = 60-00 
L atom) carbon) e.. isda a= the 
latonp azote faaneraiae dat = 17-54 
3 atoms hydrogen ...... = 3:98 
89:06 
But this analysis, however ingenious, was not performed in a 
way sufficiently rigid to produce conviction. He shows that 
when sulpho-chyazate of potash is decomposed by sulphuric 
acid and heat, that sulphate of ammonia is formed. Hence he 
concludes that the azote and the hydrogen exist in sulpho- 
chyazie acid in the same proportion in which they exist in am- 
monia ; or three atoms of hydrogen to one of azote. By de- 
composing a given weight of sulpho-chyazate of potash b 
means of chlorine, and ascertaining the weight of the sulphur, 
sulphuric acid, and carbonic acid evolved, he ascertained thac 
the sulphur and carbon in sulpho-chy4zic acid are to each other 
as the numbers 2°6 to 0-328. But these numbers are the same 
as 6 to 0°758. Now 6 is the weight of three atoms of sulphur, 
and 0-756 is very nearly the weight of an atom of carbon; so 
that this acid contains 3 atoms of sulphur and 1] atom of carbon, 
or at least the sulphur and carbon in the acid bear that ratio to 
each other. Having determined these two ratios, Grotthus as- 
certained the quantity of sulphur contained in this acid. The 
result of his experiment, which approaches very near that of 
Porrett, is that 100 parts of the acid contain 67:3 parts of 
sulphur. These were the data from which the constituents of 
the acid are estimated. The defective part of the deduction is 
