Characters. - A dark brown liquid, odourless, having a slightly ferruginous taste and acid reaction.

Reactions. - It gives the reactions of a citrate (p. 594) and a bluish green precipitate with ferrocyanide of potassium, which is increased and rendered dark blue by the subsequent addition of hydrochloric acid.

Dose. - Ten minims (06 c.c), equal to 5 grains of the salt.