4$# On the Employment of Plaiina. 
my expectation ; but, on the contrary, convinced me that 
this object, in the hands of an ingenious artist, may be 
brought to perfection. 
Gold and silver have hitherto been the only metals 
susceptible of being employed in their metallic form in 
painting and ornamenting porcelain, glass, and enamel. 
Gold answers this purpose so completely, that nothing 
further can be wished for on this head; whereas silver 
does not answer so well. As it possesses less density 
and is more porous than gold, it does not cover the 
ground so completely when applied to porcelain in thin 
leaves. The second cause of the inferiority of silver 
when employed in painting on porcelain arises from its 
nature, in consequence of which, when exposed to sul- 
phureous and other phlogistic vapours, it becomes tar- 
nished, loses its metallic splendour, and at length grows 
Mack. This inconvenience renders silver untit for be- 
ing employed in line porcelain painting, and confines the 
application of metallic substances in this manner to gold 
alone. 
Platina, in this respect, may be classed next to 
gold; and by its white colour may supply the place of 
silver without possessing any of its faults. It is not 
only capable, on account of its density and weight, in 
which it exceeds gold, of covering the ground complete- 
ly, without leaving any perceptible interstices, as sil- 
ver does ; but it withstands like gold all the variations 
of the atmosphere, as well as sulphureous and other va- 
pours.. 
The process which I employ in the application of pi a 
tina to painting on porcelain is simple and easy : it is as 
follows :— I dissolve crude platina in aqua regia, and 
precipitate it by a saturated solution of sal ammoniac in 
water. The red crystalline precipitate thence produ- 
ced is dried, and being reduced to a very fine powder 
