The double cyanide of ferrous and ferric iron, a dark blue amorphous substance having a coppery luster, used in dyeing, calico printing, etc. Cf. Prussian blue, under Prussian.
TURNBULL'S BLUE
Meaning of TURNBULL'S BLUE in English
Webster's Revised Unabridged English Dictionary. Пересмотренный полный словарь английского языка Webster. 2012