Dr. ingenhousz on Air. 
'2,6 t 
extremity into a veffel filled with quickfilver, withdraw 
the finger from within the quickfilver, and obferve to 
what height the quickfilver rifes. It requires fome prac- 
tice to perform this experiment with dexterity. 
Some time ago I got fome ounces of fi i\q platin a from 
Spain, through the means of his excellency Count 
dietrichstein, with which I made fome experiments. 
Moft writers albert, that a confiderable part of the plat in a 
is attracted by the magnet, but not the whole of it : but 
by a nice inquiry I found, that every one of the particles 
obeyed the magnet more or lefs, except fome tranfparent 
ftony particles ; and that even thefe were all magnets in 
themfelves ; or that each particle had two poles, which I 
could change at pleafure by the application of magnetical 
bars. Though their magnetical virtue is always much 
lefs than that of particles of iron, yet every one had more 
or lefs of it ; but fome fo little as not to be perceived but 
by applying a flrong magnet to them when floating upon 
water. Belldes the Hat, fmooth, and fhining bright par- 
ticles, which are alone the true platina , I find two other 
kind of particles among them; viz. fome very fmall black 
particles, moil of which are of an irregular figure, re- 
fembling the iron fand found in fome parts of North 
America; at Teneriffe; near fome lakes in Italy; in 
fome rivers in Tranfylvania, among the gold dufl, 
which is taken out of them; and in many other places. 
Some of thefe black particles, though few in compari- 
fon with the number of the irregular particles, are of a 
very regular figure; and when fcen through a good 
magnifier, fome what rcfemble the figure of a melon. 
3 Both 
