When finely divided it decomposes water giving hydrogen phosphide; it also reduces sulphurous and sulphuric' acids, and when boiled with water gives phosphine and hypophosphorous acid; when slowly oxidized under water it yields, hypophosphoric acid.
Hypophosphorous acid, HP(OH) 2, discovered by Dulong in 1816, and obtained crystalline by Thomson in 1874 (Ber., 7, P. 994), is prepared in the form of its barium salt by warming phosphorus with baryta water, removing the excess of baryta by carbon dioxide, and crystallizing the filtrate.
Wurtz's first published paper was on hypophosphorous acid (1842), and the continuation of his work on the acids of phosphorus (1845) resulted in the discovery of sulphophosphoric acid and phosphorus oxychloride, as well as of copper hydride.
The metal can be reduced by magnesium, zinc, cadmium, iron, tin, copper and substances like hypophosphorous acid from acid solutions or from alkaline ones by formaldehyde.
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