DERIVATION.--Hydrogen gas is passed over freshly made and carefully
washed ferric oxide in a hot and closed tube.
PROPERTIES.--A very fine grayish-black, lustreless powder, without odor
or taste; permanent in dry air; insoluble in water or alcohol.
DOSE.--Horses, 1 to 2 dr.; cattle, 2 to 4 dr.; sheep and pigs, 20 to 30
gr.; dogs, 1 to 5 gr.