VOL. XLVIII.] PHILOSOPHICAL TRANSACTIONS. 615 



ounce of platina and 6 oz. of pure quicksilver were rubbed together, with a little 

 common salt and water, and a few drops of spirit of salt, in an iron mortar. 

 After some hours trituration, the grains of platina became coated with the quick- 

 silver, so as to cohere into an imperfect amalgam. A part of the fluid quicksilver 

 poured off, ami evaporated in an iron ladle, left a considerable quantity of a dark 

 coloured powder, intermingled with bright shining moleculae: a part strained 

 through leather, left a smaller proportion of a similar powder. The platina, 

 which had been thus attenuated by the mercury, so as to pass with it through 

 the pores of leather, proved as refractory in the fire as at first. Exposed to a 

 very vehement heat, by itself, with borax, with white glass, it neither melted, 

 nor suffered any sensible alteration; nor did it communicate any colour to either 

 of the fluxes. 



2. One part of platina and about 4 of lead were melted perfectly together; 

 and after the heat had somewhat abated, poured gently into 3 times the quantity 

 of quicksilver, heated so as to fume. A blackish powder was immediately 

 thrown to the surface: this appeared to be chiefly platina. On grinding them 

 together, a fresh powder gradually separated; which, being occasionally washed 

 off, in appearance greatly resembled the foregoing, but was found, on proper 

 trials, to participate much more largely of the mercury and lead than of platina. 

 The amalgam, which was of a very dull colour, on exposure to the fire swelled 

 and leaped about, though the heat was scarcely sufficient to evaporate the quick- 

 silver. After constant and rapid agitation with water, occasionally renewed, in 

 an iron mill, for a week, it looked bright and uniform, and suffered the mercury 

 to exhale freely. A dark coloured calx remained, which proved, on examination, 

 to be platina, with a very little lead. 



Remark. Mercury is supposed to have a greater aflinity with lead than any 

 other metallic body, gold and silver excepted. In this experiment, it had a 

 greater affinity with platina than with lead, since it retained most of the platina, 

 after the lead, which was in much larger proportion, had been almost entirely 

 thrown out. The part of the platina, which the mercury rejected at first, and 

 that which it retained to the last, did not appear dissimilar to each other, or 

 difterent in quality from the platina employed.* 



3. A mixture of 1 part of platina and 2 of gold, which proved very white and 

 brittle, after being repeatedly nealed, was cautiously flattened into thin plates, 

 and thrown red-hot into boiling quicksilver. On trituration and ablution with 

 water, a powder separated, copiously at first, and by degrees more sparingly. 

 After the process had been contiimed about 24 hours, there was no further sepa- 

 ration, except of a very little blackish matter, into which a part of the mercury 



• Concerning the action of mercury on platina [platinum] and the compound thence formed, see 

 the interesting experiments of Mr. Chencvix in the Phil. Trans, for 1805. 



3 u 2 



