Laboratory Methods of Inorganic Chemistry, 2nd English Ed. 1928

128 OXY-ACIDS OF SULPHUR.

acid, H 2 S 6 Oe. These can be prepared only in aqueous solutions or in the
form of their salts. (Cf. Nos. 91, Barium Dithionate, and 92, Sodium Tetra-
thionate.) The acids readily change into one another, and their constitution
is doubtful.
HYPOSULPHUHOUS ACID, H 2 S 2 O 4. See No. 93.

86. Sulphuric Acid from Pyrite by the Chamber Process.
    1

Construct the apparatus shown in Fig. 20. The wide-mouthed

liter bottle is closed with a cork through which three holes are

bored. In one hole the bent-side arm of a 25 c.c. distilling flask is

FIG. 20.

inserted. A delivery tube is passed through the second boring to

the middle of the bottle and on the outside is joined to a short

combustion tube. In the third boring a tube is inserted which

leads through the safety bottle to a suction pump. Charge the

combustion tube with about 10 g. of powdered pyrite, and place a

small, loose plug of asbestos just beyond the powder to retain any

unburnt sulphur. Place about 10 c.c. of concentrated nitric acid

in the distilling flask, and insert a glass tube through the stopper so
that the lower end, which is drawn out to a capillary, reaches to

the bottom. Half fill the safety bottle with water to show the

1
From Alexander Smith and William J. Hale's A Laboratory Outline of
General Chemistry.