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SECT. VIII.

Of the Affinities of platina.

I N this section it is proposed to give an account of suchexperiments as have been made relative to the com-parative affinities of platina and other metals, to one ano-ther, and to saline dissolvents; the separation of platinafrom one metal by the intervention of another, or of onemetal from another by the intervention of platina ; the se-paration of platina by other metals, or of other metals byplatina, from their solutions in acids.. For the greaterdistinctness, the results of the several experiments are ex-pressed in the respective titles, after the same manner as inthe common tables of affinity. The body placed upper-most is always to be understood to have a greater affinityto that which is immediately under it, than to the thirdor lowermost; insomuch that if the first and third be com-bined together, the middle one, properly applied as men-tioned in the experiment, will break their union, andthrowing out the third body, join itself to the first, thoughtire separation is not always complete. Where no suchaffinity, or separation, appears in the experiment, the:several bodies are placed in a continued line.

I. Mercury :

Platina :

Lead.

One part of platina and about four of lead were meltedperfectly together, and after the heat had somewhat abated,the fluid was poured gently, in a small stream, into threetimes its quantity of quicksilver heated so as to fume. Onstirring them with an iron rod, a blackish powder was im-mediately thrown to the surface, which appeared to be:

chiefly.