Mr. Davy on a new fulminating platinum . 139 
ness. A quantity of water was then added, the whole thrown 
on a filter, and the solid matter, after being well washed* 
and dried for several days at the temperature of about 212° 
Fahrenheit, exhibited properties, which will presently be de- 
scribed. 
In preparing fulminating platinum, it may be here re- 
marked, other alkaline substances as soda, common kali, &c. 
may be substituted for pure potash. And farther, it may be 
added, nearly similar results are obtained, whether the am- 
monia sulphate of platinum be put into the fixed alkali in fine 
powder, or in a moist or wet state ; whether the fixed alkali 
be immediately added, after the precipitation from the sul- 
phate of platinum by ammonia, or the precipitate be first 
separated and partially dried, previous to such treatment. 
In making fulminating platinum, (as is the case with aurum 
fulminans,) circumstances may be varied to a considerable 
extent, without materially impairing its properties. 
III. Properties of Fulminating Platinum. 
Fulminating platinum, when prepared in the manner I have 
described, appears in the form of a loosely coherent brown 
powder. I have obtained it of different shades of colour, 
from a light brown to a dark chocolate, and even almost 
black. These varieties of colour seem to be connected with 
the agencies of the fixed alkalies, and the peculiar circum- 
stances which accompany its formation. The fulminating 
powder seems to be of a lighter or darker colour, as the 
* The washings contain a little fulminating platinum in solution, for when neu- 
tralized by nitrous or oxalic acid, a precipitate is obtained, which when washed and 
dried, exhibits fulminating properties. 
Ts 
