IRON. 



in medicine ; tliey have been named, from their colour, black 

 ami red oxyds ; tlic former, which is black, or (if formed 

 as in the prefcnt inflance, by precipitation from water) 

 greeiiifh, coMfills of iron 7^, and oxygen 2", according to 

 Lavoifier. It may bi- formed in varimis ways : as by expo- 

 fure of a pafte of iron-fihngs and water to the air ; by heat- 



ing together one part of red oxyd of iron, and two parts of 

 i-fihngs ; and by adding a folution of alkaU to one of 

 green fulphate of iron, and drying the precipitate q'.iickly 



without expofure to air ; and it is kept as a feparate article 

 in the Edinburgh Pharmacopeia, under the name of " Ferri 

 oxydjm nigrum piirificalum." The latter, or red oxyd, 

 conliils, according to Proufl, of iron 52, oxygen 48, and in 

 its relation to black oxyd is compofed of 66.5 of that oxyd, 

 and 33.5 of additional oxygen. Some chemiils have fup- 

 pofed the exiilence of other gradations of combination of 

 iron and oxygen, but the above are all that are generally 

 admitted, or that require particular notice ; this latter is 

 alfo kept in the Edinb. Pharmac. under the name of " oxy- 

 d.im ferri rubruni." Salts contaiiing the black oxyd, on 

 expofure to air, pafs to the ftate of red oxyd, by attrafting 

 oxygen from it, and in the procefs of drying, the fame 

 change happens here to the oxyd in the fub- carbonate, which, 

 at the time of its firft precipitation, is a black oxyd. The 

 fame fubftance, more impcrfeClly prepared, conllituted the 

 riift of iron {ferri rullgo) of the former Pharmacopeia, for 

 which, in all tiie pro-jeUes into which i: entered, this preci- 

 pitate is now fubltituted. The red oxyd of the Edinburgh 

 college is the old " Colcnthar vitrioli," and formed by ex- 

 pofure of common fulphate of iron to a llrong heat, fuf5- 

 cient to drive over its fulphuric acid, when the red oxyd re- 

 mains behind, as in the procefs which was formerly in ufe 

 for obtaining that acid. Sub-carbonate of foda is preferred 

 for tlie precipitation to that of potafh, on account of the 

 greater folubihty of the fulphate of the former than of the 

 latter alkah, and the confeqiient facility with which it may 

 be wallied away. Tlie fait is a fub-carbonate, but as only 

 one of the compounds is kept, the relation is not cxpreiTed. 

 The dofe of the " ferri carbonaa" is from two to ten 

 giains. 



4 " Mars fulphuratus," prepared by mixing iron filings 

 viith twice their weight of flower of brimftone, and as much 

 water as will make them into a pafte, whicii in a few hours 

 fwell up, and is then pulverized, and put into a heated cru- 

 cible to deflagrate, ar.d kept conllantly llirring with an iron 

 fpatula, till it falls into a deep black powder : this powder 

 urged longer in the fire, becomes red, and is called, 

 5. " Grocus martis aperiens et aftringens." 6. The fait or 

 vitriol of iron, " fernim vitriolatum," called "Sal martis." 

 This is now difufed. See Crocus Martis. 



This is the " ferri fulphas," fulphate of iron, of the Lond. 

 Pharm. of 1809 ; and is compofed of iron and fulphuric 

 acid, of each by weight eight ounces, and four pints of 

 water. The fulphuric acid and water are mixed together in a 

 glafs veflel, and the iron is added : then, after the effervefcence 

 has ceafed, the folution is filtered through paper, and eva- 

 porated, fo that cryllals may form as it cools. The water is 

 afterwards poured away, and the cryftals are dried upon 

 bibulous paper. Upon a large fcale this fait is formed from 

 native fulphuret of iron (pyril.'s) by moiilening, and ex- 

 pofing it to the open air. The fulpliate of iron is afterwards 

 diffolved in water and cryilallized by evaporation. Sulphuric 

 acid will unite either with the black or red oxyd: the firil 

 of thefe is the fait here intended for internal ufe, and upon 

 this point great itrefs ought to be laid ; as the lall is the 

 ftate in which the fulphate of trade is ufually found, and 

 v.'r;b, ftir medxal purpofes, is a very dillinct and inferior 



thing. Its cryftals are tranfparent rhomboidal prifms, of a 

 light green colour ; its tafte is aftringcnt and llrong, and it 

 reddens vegetable blues. One part is foluble in two of cold, 

 and in three-fourths of boiling water. It is infolnble in 

 alcohol, in which menftrunm the red fulphate is foluble, 

 and this affords a method of afcertainiug the exiftence of the 

 latter with the former, as alfo of feparating it. On expo- 

 fure to air it is gradually converted into red fulphate : it 

 confifts, according to Kirwan, of acid 26, iron 2S, and 

 water 46, parts. Heat drives off the water of cry ilallizHtion, 

 and the fait remains white ; if urged farther, it drives over, 

 the acid, and leaves firfl a red fulphate, and at laft: a redoxvil 

 of iron. The dofe of the " ferri fulpiias" is from one 

 to five grains. 7. " Tinftura martis in fpiritu falls," P. L. 

 1745, " Tinelura ferri muriate," P. L. 1787, or " Tintlura 

 ferri muriati," tindlare of muriate of iron, P. L. 18:9. 

 This is formed by pouring the muriatic acid, in the propor- 

 tion of a pint, upon half a pound of carbonate of iron 

 in a glafs veffel, and Ihaking it occafionally for three day?' : 

 then fetting it by, that the faicts, if there be any, may fub- 

 fide ; pouring off the fclution, and ndiiing three pints of 

 reftified fpirit. This fait appears to be an oxymuriate of 

 iron, the red oxyd of iron employed beco.ning, on its combi- 

 nation with the acid, black oxyd, and giving over its fuper- 

 abundant oxygen to the muriatic acid. This appears to be 

 its itate, becaufe fulphuric acid added to it detaches oxy- 

 muriatic acid, and heat drives over oxymuriatiG acid ; and 

 in the iatter inflance, although the red oxyd was ufed for its 

 preparation, the black oxyd remains- bthir.d. The fait, eva- 

 porated to drynefs, yields an orange-coloured m.afs, which is 

 uncryftaUizable, deliquefces on expofure to air, and is folu- 

 ble in alcohol. The tincture has a brownifh yellow colour, and 

 very aftringent tafte. 8. " Fl<>res martiales," P. L. 1745, 

 flowers of iron (fee Flore.s), "Ens Veneris,'' P. L. 1720, 

 " ferrum ammoniacale," P. L. 1787, or " fcrrum ainmonia- 

 tum," ammoniated iron, P. L. 1809, is compofed by inn- 

 mately mixing carbonate of iron and muriate of anmionia, 

 of each a pound, and fubliming by immediate expofure to a 

 llrong fire, and, lailly, reducing the fublimed ammoniacal u-on 

 to powder. This fubllance confills of red muriate of ir^jn, 

 mixed by fublimation with muriate of ammonia. It is orange- 

 colcured, with a fmell refembling faff^ron, is deliquefceut, and 

 foluble in alcoho'. The refidue, which is dcliquefcent, cor- 

 fi'.ts alfo of red muriate of iron, a-d was formerly kept 

 under the name of " lixivium martis." The dofe is from 

 three to fifteen grains. 9. " Tinflura florum martialiiim," 

 P. L. 1745, " Tindura martis Mynfichti," P. L 1720, 

 " Tindura ferri ammoniacalis," P. L 1787, or " TinCtura 

 ferri ammonidti," tindlure of ammoniated iron, P. L. 1809, 

 is formed by digelling four ounces of ammoniated iron 

 in a pint of proof fpirit, and theu ilraining. Thi;* is an 

 elegant chalybeate, and may be given in dofes of a tea- 

 fpoonful. 10. " Ferrum tartari/aium," or tartari/.ed iron, 

 P. L. 1787 and 1809, called alfo " Mars folubihs," and 

 " Chalybs tartarizatus," c<jnfi!ls of iron, a pound, fupertar- 

 trate of potafs, powdered, two poundv, and a pint of water. 

 Rub them together, and expofe them to the air in a broad 

 glafs veflel fur eight days, tiien dry the relidue in a fand balh, 

 and reduce it to a very line powder. Add to this powder 

 a pint more of water, and expofe it for eight days longer ; 

 then dry it, and reduce it to a very fine powder. This is a 

 triple tilt, in which the iron is firll oxydated by being 

 moiilened and expofed to air, and then combines with tlie 

 fuperabuudant acid of the fupertartate of potafs ; and it is 

 therefore a tartrate of potafs and iron. It may be difTolvtd 

 in water and cryllallizcd. This ckg.int and ufeful chal) beate 

 may be given eiihtr in a iolld or litj^uid form, from (i-.e- 



