Sulphas Ferri Exsiccatus. Edin. Dried Sulphate of Iron

"Take of sulphate of iron, any quantity. Let it be heated in an unglazed earthen vessel, on a moderate fire, until it become white and perfectly dry."

In this process the degree of heat should not exceed 212°

1 System of Chymistry, 4th edit. iii. 225.

2 Of this quantity of water, 8 parts are water of composition, the oxide being in the state of a hydrate.

3 It was used as an anthelmintic in the time of Pliny, who says, " Sumitur ad depellenda ventris animalia drachmae pondere cum melle." Nat. Hist. lib. xxxiv. cap. 12.

4 Edinburgh Med. and Surg. Journal, ii. 373.

of Fahrenheit. The salt is merely deprived of its water of crystallisation.

Officinal preparation. - Oxydum Ferri rubrum, E. D.

Limatura Ferri Purificata. Edin. Purified Filings of Iron

"Having placed a sieve over the filings, apply a magnet, so that it may draw the filings upwards through the sieve.'"

Syn. Limaille de Mars(F.), Gepulvertes Eisen (G.), Limatura diFerro (I,), Eerumboo Podia (Tam.).

The iron filings obtained from the workshops are always mixed with many impurities, and often with filings of copper and other metals. It requires some address to purify them by this process: the sieve should not be placed too close upon the filings, but as distant as the sphere of attraction of the magnet will admit of, so that the iron only may be raised

Oxidum Ferri Nigrum Purificatum. Edin. Purified Black Oxide of Iron

"Let the scales of the black oxide of iron, found at the anvil of the blacksmith, be purified by the application of the magnet: for the magnet attracts the thinner and purer scales only leaving the larger and less pure."

Ferri Oxydum nigrum, Dub. Black Oxide of Iron,

"Let the scales of iron, found at the blacksmith's anvil, be purified by the application of the magnet. Then reduce them to a powder, the finest parts of which are to be separated in the manner ordered for the preparation of chalk."

Syn. L'oxide noir de Fer (F.), Schwarzesges auertes Eisin (C), Ossido nero di Ferro (I.).

The scales struck off from red-hot iron by the hammer of the blacksmith are a mixture of protoxide and peroxide, but they still retain their magnetic quality in a sufficient degree to admit of being purified in the above manner.

Qualities. - This is an admixture of two oxides: for in heating a bar of iron, the outer layer contains the peroxide, whilst the inner is solely the protoxide

Medical properties and uses. - This mixed oxide is tonic, deobstruent, and anthelmintic. It is efficaciously administered in general debility, dyspepsia, chlorosis, and worm cases. Its utility is determined by its meeting with acid in the stomach, which is known to be the case by the disagreeable eructations it produces, and the black colour of the alvine evacuations. The dose is from grs. v. to Э j., combined with any aromatic powder, or formed into an electuary with honey, and taken twice a day.

Officinal preparation. - Tinctura Ferri Muriatis, E.