16 Mr Herscliel on the Hyposulphurous Acid. 
itself to the upper part of the vessel. Meanwhile, water distill- 
ed over, smelling slightly of sulphuretted hydrogen, and render- 
ed turbid by a minute quantity of sulphur. It weighed 49*8 
(38.3 per cent.) ; but this is undoubtedly too small, the heat of 
a lamp being not strong enough to expel all the water, a full 
ignition being requisite for that purpose. The retort was now 
v/ashed out with hot muriatic acid, which caused a copious dis- 
engagement of sulphurous acid, and 15.61 grains of sulphur 
were collected on the filter, including 0.05 obtained by evapo- 
rating the distilled fluid, and that attached to the neck and^ 
vault of the retort, which was clearly washed out by the acid. 
This sulphur amounts to 12.04 per cent., and, as we shall pre- 
sently see, is almost exactly half what the salt contains, the 
other half escaping in the state of sulphurous acid. The muri- 
atic solution, precipitated by carbonate of ammonia, gave 50.18 
carbonate of lime (38.68 carbonate, or 21.72 lime per cent.). 
To determine more exactly the quantity of water, 100 grains 
carefully dried, were brought to full ignition in a closely cover- 
ed platiiia crucible, and lost 54.05, of which, by the last experi- 
ment, 12.04 were sulphur. Hence the water amounted to 42.01. 
Sulphite of lime remained. 
To determine the quantity of acid, and its composition, 100 
grains of the standard solution, diluted in 4000 grains of water, 
were first precipitated by a large excess of pure crystallized oxy- 
nitrate of silver, and 22.45 grains of thorouglily dried sulphuret 
of silver were collected. In a second experiment, 22.37 grains 
were obtained. Taking the mean, 100 parts of sulphuret of 
silver so obtained, answer to 101.88 of the crystallized hyposul- 
phite. In both experiments, the filtered liquid, freed from its 
excess of silver by muriate of ammonia, gave a copious precipi- 
tate of sulphate on the addition of a solution of muriate of bary- 
ta, marking the production of sulphuric acid in this process. 
500 grains of the standard solution were now decomposed by 
nitrate of lead, in large excess. The precipitate, thorouglily 
waslied thrice by subsidence, then washed and drained several 
times alternately on a filter, and dried six hours on hot sand, 
amounted to 135.91 grains hyposulphite of lead. The washings, 
which were consideralny voluminous, were now treated \vith ex- 
cess of oxyiiitrate ot silver, the hyposulphite of lead though nearly 
