combinations of platinum. m 
a sufficient degree of heat is produced to reduce and ignite 
the platinum, and it remains in a state of ignition until the 
alcohol is consumed. During the agency of alcohol on the 
powder, acetic acid is produced. This is shown by putting 
a little of the powder on a paper filter and moistening it with 
alcohol ; a moderate action takes place, and in a few minutes, 
the odour of acetic acid is very perceptible. In some ex- 
periments of this kind, the action, though comparatively fee- 
ble at first, has presently increased, the powder has become 
red hot, and the bottom of the filter completely charred. If 
two or three grains of the powder are placed in a glass, and a 
few drops of alcohol added, in about half an hour acetic acid 
will be produced ; and as it evaporates and disappears, it may 
be successively renewed, at longer or shorter intervals, for 
some weeks, by occasionally adding a little alcohol. 
When the powder is boiled in alcohol, it is partially de- 
composed, and assumes a lighter colour ; if it be then thrown 
on a filter, the odour of acetic acid is soon perceived, and in 
a few hours the platinum is found reduced and the paper 
charred. When the powder is mixed with flowers of sulphur, 
and heated, a sulphuret of platinum is formed of a blue co- 
lour. When the powder is heated with phosphorus, there 
is a brilliant combustion, and a dark grey phosphoret is 
formed. Oxygen gas does not affect the powder at the 
common temperature of the air, but by a moderate heat 
there is a slight combustion, which seems to indicate the pre- 
sence of a little inflammable matter. 
3. Composition of the peculiar compound. 
In my first attempts to ascertain the nature of the black 
