METALS AND THEIIt COMPOUNDS.

Stanni PULVIS.

Melt tin in an iron vessel; pour it into anearthen-ware mortar heated a little abovethe melting point of the metal; trituratebriskly as the metal cools, ceasing as soonas a considerable proportion is pulverized ;sift the product, and repeat the process withwhat remains in the sieve.

ZlNCI OX.IDUM.

Take of Sulphate of Zinc, twelve ounces ;

Carbonate of Ammonia, six ounces ;Dissolve each in two pints of water; mixthe Solutions ; collect the precipitate on a Al-ter of linen or calico ; wash it thoroughly ;squeeze and dry it, and expose it for twohours to a red heat.

Zinci SULPHAS.

This salt may be prepared either by dissolv-ing fragments of zinc in diluted sulphuric acidtili a neutral liquid be obtained, filtering theSolution, and concentrating sufficiently forit to crystallize on cooling,—or by repeat-edly dissolving and crystallizing the impuresulphate of zinc of commerce, until the pro-duct when dissolved in water does not yielda black precipitate with tincture of galls,and corresponds with the characters laiddown for sulphate of zinc in the List of theMateria Medica.