except in a small degree so as to give the yellow colour. In this state it has been considered as a neutral muriate. By a moderately bright red heat this powder is decomposed and leaves a black spongy mass which is found to be pure platina. The insoluble muriate of platina according to Mr. E. Davy, contains 72.5 per cent. of platina, and Berzelius finds 73.3; the loss is considered as oxymuriatic acid; hence from the known proportions of this acid Berzelius infers the constituents of 100 muriate = 73.3 platina, 6.075 oxygen and 20.625 muriatic acid; or 100 platina take 8.3 oxygen. The near agreement of the above authors is favourable to the accuracy of their results; but I have found some difficulty in obtaining the insoluble muriate free from the soluble one, and at the same time from reduced platina because the precise degree of heat requisite to produce it is neither well known nor easily attained; and it is desirable that a certain weight of platina should be dissolved and the same weight reproduced as a confirmation of accuracy. From a train of experiments on the soluble and insoluble muriates of platina, the salts being obtained from the purified laminated metal, I am disposed to consider the above results as good approximations to the truth. In order to obtain the other oxide, Berzelius digests mercury in a solution of the supermuriate of platina; a black powder is thrown down, which is found to be platina, and mercury is taken up, being oxidized at the expence of the platina. It was found that 16.7 grains of mercury had precipitated 8.5 of platina; and the mercury being calculated as in the state of deutoxide, contained, from the known proportions of this metal, 1.4 oxygen; hence 8.5 platina must have yielded 1.4 oxygen; and if 8.5 ∶ 1.4 ∷ 100 ∶ 16.4; so that 100 platina must have had 16.4 oxygen in the supermuriate, or twice the quantity it had in the insoluble muriate.