Seleniate of potassa is very soluble in water, and may be obtained in small metalline grains by the evaporation of the fluid. When evaporated to dryness, the residue attracts moisture on exposure to the air. When heated to redness it fuses, and becomes of a yellow colour, but again assumes its former appearance when it cools. It is insoluble in alcohol.
Bi-seleniate of potassa is deliquescent, and soluble in water, but crystallizes with difficulty. By the applica tion of long continued heat, half of the acid is driven off. This salt is sparingly soluble in alcohol.
Quadri-seleniate of potassa cannot be obtained crystal lized. It is very deliquescent.
Seleniate of soda has the taste of borax. It is very soluble in water, and affords, on evaporation, small crys talline grains, which do not deliquesce. It is not solu ble in alcohol. By exposing this salt with muriate of ammonia to a red heat, muriate of soda is left. In this way 100 of seleniate afforded 664 muriate of soda = to 35.5 soda. The salt is therefore composed of 64.5 acid.
35.5 soda.
Bi-seleniate of soda is obtained in the crystalline state. When heated, it undergoes fusion ; and if the heat he strong, it parts with its excess of acid, and forms the seleniate. This salt is composed of 77.83 acid, 22.17 soda.
Quadri-seleniate of soda crystallizes in needles. It does not alter by exposure to the air.
Seleniate of ammonia is obtained in four-sided prisms, which are deliquescent.
Bi-seleniate of ammonia is obtained by exposing a so lution of the preceding salt to the air ; and the Quadri-seleniate of ammonia is procured by adding selenic acid to a solution of the bi seleniate, or by evapo rating the solution by heat.
Seleniate of ammonia is decomposed by heat, water and ammonia are first disengaged ; the selenic acid is then decomposed by the ammonia, and selenium is left in the retort.
Seleniate of lime is sparingly soluble ; when heated in a glass vessel it forms bubbles in the glass, and at last perforates it.
Bi-seleniate is formed by dissolving the above salt in the acid.
Seleniate of baryta is insoluble in water. It is com posed of 100 acid, 137.7 earth.
Bi-seleniate is formed by dissolving carbonate of ba ryta in selenic acid. It is soluble, and crystallizes. It
is composed of 100 acid and about 68 baryta.
Seleniate of Strontia is insoluble.
The bi-seleniate is sparingly soluble in water. By the application of heat, the excess of acid is expelled. Seleniate of magnesia is sparingly soluble. It attacks glass in the same way as the seleniate of lime.
Seleniate of alumina is formed by adding bi-seleniate of ammonia to intimate of alumina. It is decomposed by heat giving out its acid.
Seleniate of glucina is insoluble in water.
Seleniate of zzrconia is also insoluble.
Proto seleniate of iron. Selenic acid acts with diffi culty on iron. When a salt of iron containing the black oxide is added to a solution of an alkaline seleniate, the proto-seleniate of iron is precipitated. This salt is de composed by heat, and the oxide of the metal is re duced.
The bi-seleniate is obtained by dissolving the seleniate in the acid, or by adding the salt of iron to a solution of an alkaline bi-scleniate.
Per-seleniate of iron is procured by double decompo sition. It is of a yellow colour, and yields its acid by the application of ileal.
Proto-seleniate of copper is obtained by dissolving the protoxide of the metal in selenic acid. It is of a white colour.
The Per-seleniate may be formed by mixing sulphate of copper and bi.seleniate of ammonia. It is insoluble, an, ..ffurds its acid by heat.
Seleniate of lead is formed by mixing muriate of lead with seleniate of ammonia in excess. It melts un the application of caloric, and at a white heat it is decompos ed, and sub.seleniate is left in the vessel.
Seleniate of zinc is insoluble; the bi-seleniate is solu ble ; the former, when exposed to heat, generates the sub-scleniate.
Per-seleniate of tin is a white powder, insoluble in xvtacr, but soluble in muriatic acid. It yields its acid by beat.
Proto-seleniate of mercury. Selenic acid, when added to a salt of mercury, containing protuxide, throws down a white precipitate. This salt is decomposed by potassa, the alkali uniting with the acid. Muriatic acid com bines with the oxide and a little of the acid, and leaves selenium reduced.