PROPERTIES OF SULPHITES.

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apparatus. The sulphureous acid gas which is disengaged is ab-sorbed by the water in the vessel, and constitutes sulphureousacid.

2. Sulphureous acid is likewise formed during the slow com-bustion of sulphur, as directed, vol. I. p. 144.

The salts formed by the combination of sulphureous acid withdifferent bases, are called sulphites.

PROPERTIES OF SULPHITES,

All the salts of this class yield sulphur, and are converted intotulphates by heat. The nitric and oxigenated muriatic acids alsoconvert them into sulphates.

METHODS OF OBTAINING SULPHITES.

Sulphite of potash, soda, ammonia, barytes or lime may beobtained by receiving a stream of sulphureous acid gas into aconcentrated solution of the base employed, and then evapora-ting it for crystallization. Sulphite of magnesia is produced bysaturating carbonate of magnesia with sulphureous acid. Sul-phite of ammonia and magnesia is obtained by mingling togethersolutions of sulphite of magnesia, and sulphite of ammonia. Sul-phite of lead may be produced by dissolving carbonate of lead insulphureous acid. Sulphite of bismuth, and sulphite of antimo-ny are precipitated by pouring sulphureous acid into muriate ofantimony, or bismuth. Sulphite of iron may be formed in adirect manner.