Dr. ingen housz on Air . 263 
Thefe black particles of both forts, I find, are attracted by 
the loadftone, and have etich of them two poles, though 
thole of an irregular figure have them more manifeftly (*). 
The other particles are ot a gold colour; having, in gene- 
ral, more or lefsof apalenefs approaching to the colour of 
platina. Some of thefe gold particles have the figure of 
the reft of the platina , differing only from them in co- 
lour, and in not being fo bright, or as it were polifhed. 
Others are irregular mattes of indeterminate figure having 
generally a fpungy appearance. The moft part of thefe 
gold particles were evidently attracted by the magnet, and 
fire wed upon the furface of the water their two diftincft 
poles. Thefe gold particles being put upon a piece of char- 
coal, and the flame of a candle directed upon them by the. 
blowpipe of the chemical pocket laboratory, defcribed by 
gustave von engestrom, publifhed in the Englifli 
tranflation of crowns ted’s Miner alogie, run eafily into 
round balls, which have all the appearance and quality 
of real gold, except their being in general magnetical or 
having two diftincft poles. I make no doubt but this- 
magnetical quality is owing to fome platina mixed with 
the gold. I could never melt a fingle particle of true 
fhining platina by blowing ftrongly upon it with the blow- 
pipe; the only change they underwent by this operation 
was to lofe their brightnefs and the greateft part of their 
(a) If magnetifm is a criterion of iron, there nuift be. iron in the platina; 
but if the reft of this fubftance be. gold, according to fome, why fhould 
not this be precipitated together with the gold added to it, by the addition of a 
folution of green vitriol to the aqua regia in which the two metals are diftolved ?- 
mag— 
