This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1849 Excerpt: ...heated, a grey precipitate. Their solutions in acids deposit upon zinc a coating of selenium, copper-coloured at first, but afterwards becoming brown and black. Mixed with aqueous hydrochloric acid, they give with sulphuretted hydrogen a precipitate of sulphide of selenium, which is yellow when formed in tho cold, but ...
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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1849 Excerpt: ...heated, a grey precipitate. Their solutions in acids deposit upon zinc a coating of selenium, copper-coloured at first, but afterwards becoming brown and black. Mixed with aqueous hydrochloric acid, they give with sulphuretted hydrogen a precipitate of sulphide of selenium, which is yellow when formed in tho cold, but yellowish red when separated at higher temperatures. When sulphuretted hydrogen gas is passed through aqueous solution of selenite of ammonia, potassa, or soda, the same reddish-yellow precipitate is formed; but it soon turns black-brown, because the monosulphide of tho metal (or simple alkaline hydrosulphate) produced, abstracts sulphur from it, and is itself converted into pentasulphide of the metal (or alkaline hydrosulphite). On passing the hydrosulphuric acid gas through the solution for a longer time, sulphur is precipitated almost free from selenium, and the preceding compound is converted into a double sulphide of hydrogen and the metal (bi-hydrosulphate of the alkali). Boracic, phosphoric, and sulphuric acid, with the aid of heat, expel selenious acid from its salts. Hydrochloric acid has no action on the selenites. The normal selenites of ammonia, potassa, and soda, are soluble in water; the other normal selenites are nearly or quite insoluble; the biselenites and tetraselenites are easily soluble. All selenites arc soluble in nitric acid; tho lead and silver-salts, however, dissolve with difficulty. (Berzelius.) Hence those selenites which are soluble in water, give with baryta-salts a precipitate which is soluble in hydrochloric or in nitric acid. (H. Rose.) c. Selenious acid is easily soluble in alcohol. (Berzelius.) C. Sklenic Acid. SeO3. Acide selenique, Selensiiure. Formation. 1. When selenium, metallic selenides, selenious aci...
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