ARSENIATS.
When heated along with charcoal powder, they are
decomposed, and arsenic sublimes.
Sp. 1. Arsemat of Barytes.
THIS salt was formed by Scheele by dissolving bary
tes in arsenic acid. When the saturation was nearly
completed, the salt precipitated in the state of an inso
luble powder. It may be formed also by mixing arse
niat of potass with nitrat or muriat of barytes. This
salt is insoluble in water except there be an excess of
acid. When exposed to a violent heat, it shows a ten
dency to melt, but is not decomposed*.
Sp. 2. Arseniat of Strontian.
Unknown.
Sp. 3. Arseniat of Lime.
WHEN arsenic acid is dropt into lime-water, arseniat
of lime is precipitated; but if an excess of acid be add
ed, the salt is redissolved, and yields when evaporated
small crystals of arseniat of lime, which are soluble in
water, and decomposed by sulphuric acid. This salt may
be formed also by dissolving chalk in arsenic acid, or
by mixing the alkaline arseniats with the the nitrat,
muriat or acetite of lime. Arseniat of lime, when
heated, exhibits the same phenomena as the first spe
cies f.
Sp. 4. Arseniat of Magnesia.
MAGNESIA dissolves in arsenic acid ; but when the
acid is nearly saturated, the solution becomés thick and
Ibid. p. 157.
& Scheele, i. 163.
Bb4
591
Chap. III.
Character.