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little time looked of a dark olive colour, and soon afterwere covered over with a reddish brown matter.. Theliquor became at first darker coloured, and afterwards, bydegrees, as the precipitate fell, nearly colourless, withoutexhibiting the least appearance of a purplish or reddish hue.

Some platina was digested in a quantity of aqua regiasufficient to .dissolve only about half of it, and the remain-der was dissolved in a fresh portion of the menstruum.The two solutions, treated as above, yielded somewhatdifferent phenomena, but no tendency to a purplish castcould be perceived in either. The latter solution, whichlooked yellow from its not being fully saturated with theplatina, was, when diluted with water, almost colourless:nevertheless., on the addition of tin, it became yellowagain, then of a dull red, and at last of a dark brownishred, considerably deeper than the other more saturated so-lution: on standing for some time it grew perfectly clear,depositing a paler yellowish precipitate.

To . determine whether platina was capable of pre-venting a, small proportion os gold from discovering itselfin this way of trial, one drop of a solution of gold was letfall into, some ounces of a diluted solution of platina. Onadding some plates of tin, the liquor became quickly purple.

The foregoing experiments were made with a solutionof the picked grains of platina. I submitted also to thefour last trials, with tin, æther, essential oils, and vinousspirits, a solution made by digesting in aqua regia the en-tire mineral, with its mixture of yellow particles, as itcomes to us ; which solution, in all these trials, gave ex-actly the same appearances, as the other solution did afterit had been first mixed with a very little quantity of so-lution of gold, striking a purple colour with tin, com-municating a yellow tinge to, æther and essential oils, andyielding a yellow film with rectified spirit of wine.

XIV. Precipitate.