Oil of Vitriol, [64], [65], [67]. Sulphuric acid.

Old Fustic, see [Fustic].

Old Gold, [109], [112-114].

Olive, [109], [113], [118], [135].

Onion skins, [128].

Orange, [91], [93], [102], [106], [109], [120], [132]; from lichens, [48], [51], [58], [60-2].

Orchil, [45], [52-55].

Organzine. Twisted raw silk from best cocoons, used for warp.

Orseille, [58].

Oxalic Acid, [30], [31].