IRON. 301 



Oxides of Iron. 



Protoxide, or Black Oxide of Iron. Ferri Squama Oxidi, 

 Ph. D. — This oxide is the scales of iron detached by the hammer 

 of the smith from the surface of the iron when it is red hot. It is 

 attracted by the magnet, and when freed from impurities in this 

 way, constitutes the " Oxidum Jerri nigri pmificati," of the 

 Edinburgh pharmacopoeia. It is used only in making the 

 " Tinctura muriatis ferri." 



Peroxide, or Red Oxide of Iron. Oxidum ferri rulrum, 

 E. D — This oxide is formed by exposing the black oxide to air at 

 a high temperature, or, as directed in the pharmacopoeias, by 

 calcining the dried sulphate of iron at an intense heat, until it 

 becomes of a deep red colour. It was formerly named Colcothar, 

 or caput mortuum vitrioli, and is employed by the Edinburgh and 

 Dublin colleges in making the " Marias Ammonia? et ferri." 



Sub-carbonate, or Rust of Iron. Ferri Sulcarlonas, Ph. L.; 

 Ruligo Ferri. — This is a peroxide of iron, containing a very small 

 proportion of carbonic acid. It is prepared by exposing filings of 

 iron wire, cut in small pieces, to air, and then frequently moisten- 

 ing them with water, till they are converted into rust. By this 

 process, the metal is oxidated at the expence of the water, which 

 is decomposed, while, at the same time, carbonic acid is absorbed 

 from the atmosphere and combined with the oxide. 



The Carbonas ferri precipitatus, of the Edinburgh College, is 

 prepared by adding a solution of carbonate of soda to a solution of 

 sulphate of iron. It is also a sub-carbonate, and agrees in its medi- 

 cinal properties with the rust. The rust of iron is a useful tonic 

 and emenagogne, and may be administered in all cases where 

 chalybeates are indicated. It is inodorous, insipid, and insoluble 

 in water ; hence it is commonly given in the form of pills, com- 

 bined with bitters and aromatics, or with aloetics, valerian, and 

 myrrh. Its usual dose is from five grs. to si. As a remedy in 

 tic doloreux, it is given in the dose of from half a drachm to a 

 drachm. In chorea, this preparation of iron has been administered 

 with great success in doses of two drachms twice or three times 



a-dav. 



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