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V. Separation by inflammable liquors.

Inflammable spirits, which revive gold from its so-lution in form of yellow films, have no such action on:solution of platina. This experiment affords a sure crite-rion for distinguishing whether gold has been debased byplatina, or whether platina holds any gold, and likewisean infallible method of recovering the gold perfectly pure.

If the compound be dissolved in aqua- regia, the solutionmingled with twice its quantity or more of rectified spiritof wine, and the mixture suffered to stand for some daysin a glass slightly covered, the gold rises to the surface,leaving the platina dissolved. The golden pellicles maybe collected, by pouring the whole into a filter just largeenough to contain it : the dissolved platina will passthrough, leaving the gold upon the paper, which is to bewashed with fresh portions of hot water till the liquor runsthrough perfectly colourless. The paper is then to besqueezed together, and burnt in a crucible previously rub-,ed on the inside with chalk, which prevents the small par-ticles of the gold from lodging in the cavities : when thematter has fully funk down, some nitre is to be added,and the fire increased to bring the gold into fusion. Thisprocess is accompanied with one inconvenience, the slow-ness of the separation of the gold from the solution : thismay be somewhat expedited, by employing a spirit thathas been distilled off from such vegetables as give over anessential oil.

The fame intention is answered'very speedily, by pureessential oils. The metal to be examined being dissolvedin aqua regia, add to the solution about half its quantityof any colourless effential'oil: shake them well together,and then suffer them to rest : the oil rises immediately- totjie surface, carrying the gold with it, and leaving the pla-tina t