2. A more convincing proof, that part of the platina remains suspended, after the precipitation of the gold, was obtained, by putting into the filtered liquors some plates of pure tin, which presently contracted an olive hue, and threw down a large quantity of a brownish precipitate, as from the common solutions of the crude mineral. It was observable, that the tin plates were often sensibly acted on, even whilst the liquor was overcharged with alkali. 3. It has been further suggested, and with great appearance of probability, that as a part of platina is precipitated as well as gold by alkaline salts, if only this part be mixed with gold, it will be thrown down by them again upon dissolving the compound. To determine this point, a precipitate of platina made by fixed alkali was melted with thrice its weight of fine gold, and kept in strong fusion for above an hour: they united more easily than gold does with so large a proportion of the crude mineral, and formed a smooth neat bead, which hammered well into a pretty thin plate before it cracked, and appeared internally uniform and equal. This compound being dissolved in aqua-regia, and a fixed alkaline salt added by degrees till the acid was more than saturated, the liquor became indeed pale; but tin plates put into it quickly discovered, that it held a very considerable quantity of platina. It appears therefore a constant property of this mineral to remain partially dissolved in the neutralised liquor; and that minute proportions of it, mixed with gold, are by this means distinguishable. 4. Many other experiments were made of the precipitations and precipitates of gold and platina, by alkalies both of the fixed and volatile kind. The most remarkable effects were, that volatile alkalies, added to both solutions in quantity just sufficient to saturate the acid, precipitated gold intirely, but platina only in part, so much of it remaining suspended as to give the same colour to the liquor as when fixed alkalies were made use of: that, on adding a larger quantity of the spirit after the precipitation of the gold, the liquor became yellow, a part of the metal being taken up again; and that the platina was more copiously redissolved, the liquor becoming of a deep brownish red: that the washed precipitates of both metals, whether made by volatile or fixed alkalies, proved soluble, by moderate digestion, in spirit of salt; those of platina much more difficultly and sparingly than those of gold. 3. _By inflammable Liquors._