52 Mr. Wilson’s Account of Dr. knight’s 
fmaller parts as would remain fufpended in the water for 
a time. The obtaining of thofe very fmall particles in 
fufficient quantity feemed to him to be one of the prin- 
cipal defiderata in the experiment. 
The water being by this treatment rendered very 
muddy, he poured the fame into a clean earthen veflel, 
leaving the filings behind; and when the water had 
flood long enough to become clear, he poured it out 
carefully, without difturbing fuch of the iron fediment 
as ftill remained, which now appeared reduced almoft to 
impalpable powder. This powder was afterwards re- 
moved into another veflel, in order to dry it ; but as he 
had not obtained a proper quantity thereof, by this one. 
itep he was obliged to repeat the procefs many times. 
Having at laft procured enough of this very fine pow- 
der, the next thing to be done was to make a pafte of it, 
and that with fome vehicle which would contain aconfi- 
derable quantity of the phlogiftic principle ; for this pur- 
pofe he had recourfe to linfeed oil in preference to all 
other fluids. 
With thefe two ingredients only he made a ftiff pafte, 
and took particular care to knead it well before he 
moulded it into convenient fhapes. Sometimes, whilft 
the pafte. continued in its foft ftate, he would put the 
impreffion 
