Black Ochre

: ON THE NEUTRAL, BLACK.

Earth Black, or Prussian Black, is a native earth, combined with iron

and alluvial clay. It is found in most countries, and should be washed

and exposed to the atmosphere before being employed. Sea-coal, and

other black mineral substances, have been and may be used as substitutes

for the more perfect blacks, when the latter are not procurable, which

now seldom or never happens.



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