[ 49 ° ]

perly heated, nearly on the same principle as humid men-strua dissolve them.

I. Platina with Borax.

Half an ounce of platina was dropt into an ounce ofmelted borax, and urged with an intense fire for an hour.The platina appeared to have suffered no alteration, but theborax was changed to a dark blackish colour, probably fromits having dissolved and vitrified some of the ferrugineousdust. The whole was returned to the sire, which was keptup strong for a considerable time longer, till the borax hadfunk through the crucible : it left the grains of platina ofa bright white colour, slightly cohering but unaltered inform.

II. Platina with Alcali.

I treated platina in the fame manner both with thecommon fixt alcaline salts well purified, and with thecaustic alcali prepared by evaporating soapboilers ley, butcould not perceive that either of them had any other effectthan contributing to brighten its colour. Mr. Marggrafmixed a dram of platina with half an ounce of salt oftartar, and gave .them a vehement fire, in a close lutedcrucible, for two hours. When cold, he found a hardmixt, of a yellowish green colour, in which the platina wasdispersed. The whole being separated, as much as possi-ble, from pieces of the crucible, by scraping and washing,the water above the matter was next day found like gelly:the platina was whiter than usual, almost of the whitenessof silver, but of its wonted figure. The gelatinous con-sistence which the water acquired in this and some of thefollowing experiments, is probably not owing to the pla-tina, but to some of the earth of the crucible dissolved bythe saline matter.

III. Platina