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attionSy renders any recapitulation of the difcoveries 
hitherto made unneceffary. 
The near and remarkable relation betwixt platina 
and gold, not only in point of gravity, but in many 
lefs obvious properties, hitherto fuppofed to belong 
to gold alone ; and their as manifest difagreement in 
others, particularly colour, duCtility, and fufibility j 
induced me to examine, what effects they might have 
in combination with one another in different propor- 
tions ; and whether there is reafon to credit the re- 
port of great frauds having been committed by mixing 
them together j how far fuch abufes are practicable > 
and, what is of more importance, the means by 
which they are difcoverable. 
Experiments of the Mixture of Platina and Gold. 
Experiment I. 
i. Twelve carats* of fine gold, and the fame 
quantity of the purer grains of platina, were urged 
in a blaft -furnace, for near an hour, with a fire fo 
jftrong, that a flip of Windfor brick, with which the 
crucible was covered, tho’ defended by a thin coating 
of pure white clay, had begun to melt. Upon break- 
ing the veffel, the metal was found in one fmooth 
lump or bead ; which, after being nealed by the 
flame of a lamp, and boiled in alum-water, appeared. 
* The proportions were adjufted according to the carat weights, 
as it is by thefe, that the finenefs of gold is ufually exprefted. A 
carat is the twenty-fourth part of the whole compound : thus gold 
of fo many carats is a competition, of which fo many twenty- 
fourths are fine gold, and the reft an inferior metal. 
both 
