398 Mr HerscIiePs Additional Observations 
sulphuric acid is formed. The theory of this change is 
|b + 2(S + 0)| + |(S + 0) + (S+30)| 
= |b + (S + 3.0)|h-(S + 4) + (S + 3 0). 
The nitrate is converted into hyphosulphite or sulphuret^^ 
according to the relative proportions of the salts present, their 
degree of dilution and temperature. 
I have already noticed the tendency of this acid to form 
double salts with the oxide of silver and various bases. Of 
these there appear to be two distinct genera, differing remark- 
ably in solubility, and in other characters as well as in the pro- 
portions of their component salts. The double salt, with base 
of potash, has been described ; and we need only add, that as 
it precipitates not only when the carbonate, but also the sul- 
phate, nitrate, and probably any neutral salt of potash is pour- 
ed into a saturated solution of muriate of silver in hyposulphite 
of soda, it may perhaps become a useful test of the presence of 
the former alkali, the salts of soda producing no such precipi- 
tate. 
Hyposulphites of Soda and Silver. — When the last mention- 
ed solution of muriate of silver is evaporated gently, a copious 
formation of thin silky plates takes place, aggregated in tufts, 
and mixed with a good deal of deposited sulphuret of silver. 
They have a most intensely sweet taste, and are easily soluble 
in water. The same solution allowed to cool, after a very 
slight evaporation, deposits a small quantity of minute, hard, 
brilliant crystals, in the form of lance heads, with a very sharp 
and a very blunt point opposite each other, or flattened six- 
sided prisms terminated by dihedral summits. They are not 
very soluble, have a sweet taste, blacken by heat, melt and give 
a bead of sulphuret of silver enveloped in a saline scoria. I 
could not collect enough for analysis. 
Hyposulphites of Ammonia and Silver. — When hyposul- 
phite of ammonia is poured on muriate of silver, it dissolves it ; 
and if into the saturated solution alcohol be poured, a white salt 
is precipitated, which must be violently expressed between blot- 
B = base; S, sulphur; s, silver; 0, oxygen. 
