Page:Proceedings of the Royal Society of London Vol 1.djvu/143

Rh Reﬂecting, however, upon the various modiﬁcations which sub- stances undergo when in union with each other, and on the varia- tions produced in the laws of afﬁnity by the intervention of new bodies, he was induced to try whether, by the afﬁnity of platina with some other metal easily reduced, and the interference of an interme- diate agent, a reduction of both metals might not be brought about, although no such effect could be produced upon each metal when separate. Mercury was thought the most likely to succeed, as being the most reducible; and the intermediate agent adopted was green sulphate of iron. A solution of this sulphate was poured into a salt of platina, and also into a salt of mercury; in neither of which any precipitate took place. The two liquors were then united, and a precipitate, exactly resembﬁng that which is formed by green sul— phate of iron in palladium, was instantly formed. This precipitate" was collected and exposed to a strong heat, and a metallic substance was obtained, not to be anyways distinguished from palladium.

Thus, after having been bathed in his attempts to discover, by analysis, the component parts of this substance, which he could never bring himselfto consider as a new metal, a synthetic process at length led him to the discovery, that the whole pretence was an imposition, and that the substance is, in fact, a combination of platina and mer- cury; in which the latter, while it marks the most characteristic pro— perties of the former, loses the greater number of its own distinctive qualities.

The singular fact, that an alloy of two metals should be produced, the speciﬁc gravity of which is little more than one half of what it ought to be by calculation, is, no doubt, worthy of particular atten- tion; and as quicksilver was in this process brought to a ﬁxed state under circumstances never before observed, a notion might be enter- tained that the great desideratnm in alchemy, the ﬁxation of mercury, was by no means a visionary object. This anomaly of the true and the calculated speciﬁc gravities of alloys has been attended to with great caution; and we ﬁnd the results of the inquiry collected in a‘ table, in which are entered the true and the calculated speciﬁc gra- vities of palladium'with seven different metals; and the differences are stated, which vary much more considerably than might have been expected, both in excess and defect, the number representing this difference in the combination with platina being +2100, and with tin —- 1'165.

‘ Those who cultivate chemistry with any degree of ardour, will be gratiﬁed to see in this paper the pains taken by the author, and the various modes he has devised, to produce this compound metal in its most perfect state of combination. Among various other results, it appears that the speciﬁc gravities of the alloys vary according to the proportions of the two ingredients in the following manner:— Should this alloy ever be found useful in the arts, or for (Economi-