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tated by : the author observes that this appears moresensible in our precipitate of platina, at least with regardto the dissolvent, than in most others; and that this ob-servation discovers the cause of sundry singular phenomena,which I had remarked in the precipitation of platina, andof which I had not given the theory, as of the red preci-pitate being soluble in water, and of part of the platinaremaining suspended whatever quantity of alcali we addin the cold: a detail and explication of these phenomena,with others of the same nature, he reserves for anothermemoir. Some experiments I have made do not very wellagree with this theory, but I forbear any further observa-tions till the authors memoir appears.

VII. Solution of platina , with mineralfxt alcali.

A 8 the two foregoing kinds of alcaline salt precipitateplatina only in part, there is a third which has not eventhat effect. The mineral alcali or basis of sea salt, themethod of preparing which will be described in the fol-lowing part of this history, produces no precipitation atall. This remarkable experiment, which we owe toMr. Marggraf, will be further considered hereafter.

VIII. Solution of platina, with Prufian alcali.

Mr. Marggraf observes, that when solution of pla-tina is mixed and saturated with a lixivium of fixt alcalithat has been calcined with blood, it yields a sine blueprecipitate, which in certain circumstances proves as beau-tiful as the best Prussian blue, though there falls also atthe same time a little orange coloured matter. On re-peating this experiment, the liquors when first mixed ap-peared of a pretty deep blue, but when the precipitatehad settled, greatest part of it looked yellow, on account,probably, of the platina I made use of containing less fer-

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