Ferrotype, or ENERGIATYPE, a photographic process, first made public by Robert Hunt in 1844, in which the negative was developed by a saturated solution of protosulphate of iron, with mucilage of gum-arabic, and fixed by soaking in water to which a small quantity of ammonia or hypo-sulphite of soda had been added.
Ferrotype
Chambers's Encyclopaedia, Volume 4: Dionysius to Friction, p. 593
Source scan(s): p. 0608