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air furnace, in a heat that would melt cast iron in fif- 

 teen minutes, without being either melted or wasted. 

 But when exposed to a proper heat with gold, silver, 

 copper, lead, or tin, it readily melts and incorporates 

 with them. Having been kept in an assay. furnace 

 with lead for three hours, till all the lead was wrought 

 off, it was found remaining at the bottom, without 

 having suffered any alteration or diminution. A piece 

 of it was put into strong aquafortis, and kept in a 

 sand-heat for twelve hours, yet when taken out it,was 

 no ways corroded, and was of the same weight as when 

 put in. It has been said to be heavier than gold : but 

 that is a mistake. Its specific gravity is to that of 

 water, as fifteen to one. Yet an equal mixture of 

 gold and platina, was near as heavy as gold itself, 

 being to water as nineteen to one. It appears then, 

 that no known body comes so near gold in fixedness 

 and solidity. If it could be made as ductile as gold 

 it would not easily be distinguished from it. 



Flatina is likewise found in large, hard masses: these 

 masses are with great labour, reduced into small grains, 

 which arc afterwards ground with mercury to extract 

 the gold ; and it is not to be brought into fusion by 

 the greatest degree of fire procurable in the ordinary 

 furnaces. It entirely resists the vitriolic acid, which 

 dissolves or corrodes every other known metallic body 

 except gold. Nay, it resists the marine fumes, and 

 the regal cement, 30 called, from its being supposed 

 to purify gold from all heterogeneous metallic matters. 

 It also resists the force of the vitriolic and nitrous 

 acids, though applied in such a manner as to be ca- 

 pable of perfectly dissolving all other known metallic 

 bodies. It follows from other experiments, that, pla- 

 tina contains no gold ; for it cannot, any more than 

 the common metallic substances, prevent a small por- 

 tion of gold mixed with it from being discoverable. It 

 farther appears, that platina, like gold, is not acted on 

 by the simple acids which dissolve every metallic body 

 besides : that aquae regiae, the solvents of gold, prove 

 menstrua for platina; aud that consequently the com- 



