METHOD OF OBTAINING l'LATINA.

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METHOD OF OBTAINING PLATINA.

The processes most commonly employed to obtain pure pla-tina, are as follows:

1. Take equal parts of platina in grains, and acidulous tartriteof potash, put the mixture into a well luted crucible, and exposeit for two hours to a violent heat. The platina fuses, but itbecomes brittle and whiter than platina is in common ; then ex-pose it to a very strong heat under a muffle, by which meansall the arsenic combined with it will be disengaged, and theplatina remain behind in a malleable state.

2. Platina may likewise be obtained pure, by decomposingthe nitro-muriatic solution of common platina, by muriate of am-monia, heating the precipitate intensely, and stamping it whenof a white heat into one mass : or, by assisting the fusion witha stream of oxigen gas.

3. Jannetty’s process, which is considered as the best, andwhich is generally used for obtaining malleable platina, is asfollow's :

Triturate common platina with water, to wash off every conta-minating matter that water can carry away. Mix the platinawith about one-fifth part of arsenious acid and one fif-teenth part of potash; putting the whole in a proper cruci-ble, in the following manner : Having well heated the crucibleand the furnace receiving it, put in one-third of the mixture,apply to this a strong heat, and add one-third more : aftera renewed application of heat, throw in the last portion. Aftera thorough fusion of the whole, cool and break the mass. Thenfuse it a second time, and, if necessary, even a third time, tillit ceases to be magnetic. Break it into small pieces, andmelt those pieces in separate crucibles, and in portions of apound and a half of the platina to each crucible, with an equalquantity of arsenious acid and half a pound of potash. After

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