This preparation of iron was brought into notice, a few years since, as a powerful styptic, by M. Monsel, surgeon to the military hospital at Bordeaux; and was introduced into the U. S. Pharmacopoeia at the late revision. It is prepared by boiling powdered sulphate of iron in a mixture of dilute sulphuric and nitric acids until red vapours cease to escape, and the liquid becomes of a deep ruby colour. The object of the nitric acid is to sesquioxidize the protoxide of the sulphate, and of the sulphuric acid to meet the demand of the sesquioxide produced for a greater amount of acid to saturate it; but, as the quantity of sulphuric acid is not sufficient to neutralize the whole of the sesquioxide produced, the result is necessarily a subsalt of the sesquioxide; and this, therefore, is correctly designated in the Pharmacopoeia as subsulphate.

* In a communication to the London Medical Times and Gazette (xiii. 64), it is stated by the writer that he had found the use of rhubarb, conjointly with the sulphate of iron, to prevent the blackening of the stools occasioned by the latter medicine, as by other chalybeates, when used alone, or in other form of combination. (Note to the second edition).

The solution is inodorous, of a deep reddish-brown colour, and of an extremely styptic taste, without causticity. Its sp.gr. is 1.552. When evaporated to dryness, it yields a reddish salt, which is soluble in water and alcohol without decomposition. It is thought to contain 2 eqs. of sesquioxide of iron and 5 eqs of sulphuric acid (2 Fe2O3, 5 S03), and is probably a double salt, consisting of one eq. of tersulphate of sesquioxide of iron (Fe2O3, 3 So3) and one of bisulphate of the sesquioxide (Fe2O3, 2 So3).

The property to which it owes its therapeutic value is that of producing a speedy and firm coagulation of the blood, whereby it is enabled to arrest hemorrhage more quickly and effectually than most other styptics; while it is less irritant than the other medicinal sulphates. It is used to suppress bleeding from wounds, also spontaneous hemorrhage from the mouth, nostrils, and fauces, and from the uterus, whether active or passive. It is said to have proved peculiarly efficacious in chancre.

The solution has also been used internally, and, in consequence of its exceeding astringency, with little relative irritating power, would seem to be peculiarly applicable to hemorrhage from the stomach and rectum; being swallowed in the former case, and administered by enema in the latter. It may be given in the dose of from three to ten drops.