Acetate of protoxide of iron is in small, green crystals, which decompose rapidly on exposure to the air; acetate of sesquioxide of iron is uncrystallizable, and, in the solid state, deliquescent; it is only, therefore, in solution that either of these salts can be conveniently kept. The Dublin Pharmacopoeia directed a Tincture of Acetate of Iron (Tinctura Ferri Acetatis), which was made by mixing alcoholic solutions of the sulphate of sesquioxide of iron and acetate of potassa. A double decomposition took place, resulting in the formation of sulphate of potassa, which was precipitated, and acetate of sesquioxide of iron, which remained in solution. The liquid was then expressed and filtered. The tincture thus made is transparent, of a deep-red colour, and a strong, ferruginous taste. It is an agreeable and efficacious chalybeate, and was a favourite with Dr. Percival, who is said to have introduced it into the Dublin Pharmacopoeia. In this country, it is seldom or never used. The dose is from twenty minims to a fluidrachm.