ALUM

A salt composed of alumina, potash, and sulphuric acid, and in its usual form containing a large quantity of water of crystallisation. Its octohedral crystals consist of Alumina... 3 atoms = 54 10 76 Pota a - - - 1 " =48 0-95 Sulphuric acid - - 4 " =100 33-74 Water - - ■ 24 " =216 45-55 Crystallised alum - 1 =478 100 00 Alum di olves in about five parts of water at 60°. The solution has a sweet and astringent taste, and is a powerful Styptic. When crystallised alum is heated, it melts, and gradually losing water of crystallisation, becomes a white ma , called burned alum. Alum is largely manufactured for the uses of the arts, especially dyeing and calico printing. What is termer! alum ore, is an albuminous slate, containing sulphuret of iron; i! is calcined, exposed to air, lixiviated, and the solution so obtained mixed with sulphate of potash, and crystallised.The alum works near Paisley, and at Whitby, in Yorkshire, are the largest in England. Milk, curdled by stirring it with a lump of alum, Atrium whey, which is sometimes taken as a remedy for relaxed bowels. Alum curd is made by beating the white of eirg with a piece of alum till it coagulates. [s. 52]