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Spongy Platinum

Dissolve separately crude bichloride of platinum, and sulphur in excess; and the liquor containing hydrochlorate of ammonia in proof spirit; the re-dissolved precipitate gives a yellow of add the one solution to the other as long as a orange-yellow precipitate on the addition of BISMUTH-ALLOYS. an acid. Ammonia, and potassa, and their acid; add caustic potash in excess, and the carbonates (excepting in solutions of tartar oxides of bismuth and lead will be precipitated, emetic) give a bulky white precipitate; that but the lead oxide will be at once re-dissolved from ammonia being insoluble in excess of the by the alkali. The oxide of bismuth can then precipitant; that from potassa readily so; be separated by filtration, washed, and igniwhile those from the carbonate are only solu- ted. (Makins.) ble on the application of heat. 3341. To Estimate the Purity of Antimony. Treat pulverized antimony with nitric acid; this oxidizes the antimony, and leaves it in an insoluble state, whilst it dissolves the other metals. Collect the oxide cn a filter, wash, dry, ignite, and weigh it.

This weight, multiplied by 843, gives the weight of pure metal in the sample examined.

If this has been previously weighed, the percentage of pure metal is easily arrived at. Alloys.

Alloys. Combinations of the metals with each other obtained by fusion.

When mercury is one of the component metals, the compound is termed an amalgam. (See No. 3532.) Most of the metals unite with each other by fusion or amalgamation, and acquire new properties. Thus: copper alloy-