v. . LU. 



METALS. 



..f mmmJir u extensively uatda* source of sulphur 

 in tb> itn-"*"~ of mlpbuno aokL Some varieties of it decompose 

 to air, being gradually converted into sulphate of iron. 



Fed 

 Fe.Cl, 



Jrm and eahrtM form two 



I. rrotoeUorU* of Iroa 

 J. Ptrealctide ofiroo 



I. PntotUoridt of iron in the anhydrom rtate (FeCl) i obtained on 

 pMnng dry hydrochloric acid ga* over iron filing* heated to redness, 

 hydrogen is evolved, and the salt sublimes in white micaceous scales. 

 In the hydratod condition it may bo prepared by dissolving iron in 

 hydrochloric acid, and evaporating in vacuo; green crystals are then 

 produced (FeCl + 4 Aq.), which most be preserved in an atmosphere 

 of hydrogen or of carbonic acid. 



Other jtal may be coated with iron by boiling them in a solution 

 of protochluride of iron containing chloride of ammonium and pieces 

 . : . .-. i 



L PmUoritU of iron (Fe,Cl,> (ie*puMoridt). Obtained in brown 

 > psxlng exeeas of chlorine over iron heated to redness. It 

 at a red heat, is soluble in alcohol or ether, and is very 

 The hydrattd perckloride is deposited in large red 

 uisisls on evaporating a solution of the hydrated peroxide in hydro- 

 chloric acid. They contain six equivalents of water of crystallisation. 

 Solution of perchloride of iron has a great tendency to dissolve per- 

 oxide, and on evaporation the solution yields a confusedly crystalline 

 a*** of uncertain composition. The following is a convenient method 

 of preparing a definite solution of perchloride of iron. Five parts of 

 iron filings are dissolved in twenty parts of the common strong 

 hydrochloric acid, the liquid filtered through asbestos, three additional 

 parte of the acid then poured in, and the whole heated to ebullition; 

 nitric acid is now gradually added till no more red fumes are evolved, 

 wh. n the iron will all be in the state of perchloride. If necessary, 

 the solution may be evaporated to the crystallising point ; if carefully 

 prepared it will contain no free acid. 



Solution of perchloride of iron mixed with alcohol forms the tincture 

 of HtqmcUaride of iron used in medicine. 



Iron and iodine, 



Iron and bromine, and 



Iron and .rfioriiK- form combinations corresponding to tho two chlo- 

 ride*. The only one of importance is the 



Protmudide of inn (Kel). This salt U used in medicine, and is 

 prepared by boiling iodine with excess of iron filings, or small nails, in 

 water. On evaporation, the solution yields green crystals, containing 

 Fel + 4Aq. These crystals fuse on the application of a moderate heat, 

 give off their water of crystallisation, and on cooling solidify into a 

 steel-grey crystalline mam. In manipulating with iodide of iron, con- 

 tact of air should be avoided a* much as possible, as an oxyiodide is 

 very apt to form ; the operations should also be conducted in iron 

 Yes**!*, sod when in solution a piece of iron wire should be immersed 

 in Uie liquid. 



ProtoeartKMaU of iron (FeO, CO,) occurs native. It is from this ore 

 that most of the English iron i* obtained. [IRON, in NAT. HIST. Div.l 

 It also exist*, dissolved by the aid of carbonic acid, in certain natural 

 water* or chalybeate springs. It may be formed artificially by precipi- 

 teiisga protesaH of iron with an alkaline carbonate: at first it is white, 

 but rapidly lose* carbonic acid, absorbs oxygen from the air, becomes 

 green. Mack, and finally red (peroxide of iron). This change may be 

 considerably retarded by mixing it while moist with powdered white 

 sugar, sad rapidly drying over a water-bath ; it then constitute* the 

 i / iron tfilA ngnr of the London Pharmacopoeia. 



of iron are numerous, but ill defined. The principal are 



1. Phosphate of protoxide of iron. 



2. I*ho*|ihate of peroxide of iron. 



8. Pyrophosphato of peroxide of iron. 



1. Pkoqilalt of protoxidt of iron, or protopknohate of iron (2FeO, 



O v or3P*0,POA This U obtained a. a white precipitate on 

 adding ordinary Uibasic phosphate of eoda to protosulphate of iron. It 

 is insoluble in water, but soluble in solution of phosphoric acid, and 

 the latter liquid, when mixed with sugar, constitute* the tynp of phot- 

 jUdte (or mptrpnoqJult) of iron used in medicine. 



2. Pkotflau f >*rwfe of iron, or pwpnotpnati of iron (Fe,0 M 

 PO, + 4Aq. ), falls u a white precipitate on mixing solution* of a persaft 



n sod ordinary tribute phosphate of sod*. Unlike the pi.. to 

 phosphate, H does not absorb oxygen from the air, and, being of 

 eoosunt composition, is frequently used in quantitative analysis a* a 

 BMao. of estimatinc nbosphoric acid. It i. insoluble in acetic acid, but 

 salable u solution of persecute of iron. 



t. PrrafkofftiaU ofptnaidt of iron (pynpkotpkale of iron), (2Fe 

 PO. Aq.), a white powder produced by double decomposition of a 

 pers.lt ..f ir,,i. ,U. diUc pho.phate (or pyropboiphate) ofsoda. It 

 u iosiJuble n. water or in dilute acids, but soluble in alkaline pyro- 

 plraphste. or citrates, such solutions yielding, when evaporate/ to a 

 ynip and spresd over gla*. plates, bsautiful transparent scsle* of 

 yellowish-cram or ml colour. They are used in medicine under 



various names, the ritro-amtnmlanil-jiyroj.fiotjifiate of iron and tvdo. 



lag < . ::... 



iron are two : 



1. Protosulphate of iron. 



2. Persulphate of iron. 



1. ProtontlpJiale of iron. Oreen ritriol. Coppenu. (FeO, SO, * 

 This salt i* largely produced in the manufacture of ALUM. It is also 

 formed in the prooes* for precipitating copper from the solut 

 sulphate of copper obtained in certain metallurgical operation* -.,,;], 

 that metal. Old scrap iron is used for this purpose, and, i 

 copper in solution, U obtained as sulphate of iron on evaporating the 

 li.juor. .Sulphate of iron may be formed on the small scale by dissolving 

 iron in dilute sulphuric acid. The following decomposition take* 

 placo: 



Fe + HO, 80 j = FeO, SO, + H 



Iron. Sulphuric acid. 



Sulphite of 

 iron. 



Hydrogen. 



On evaporating the solution the salt crystallises out in beautiful 

 bluish-green rhomboidal crystals. These, however, like all the 

 salts of iron, must be exposed as little a* possible to the air, for they 

 quickly absorb oxygen, and a separation into basic and neutral pcnalts 

 results, thus : 



4FeO; 80, + O, = Fc.O,, SO, + Fe.O,, SSO, 



Protonulphatc Oxygen. tiutaulphate Fenulpkatc 



of Iron. of iron. of iron. 



Submilphates of other composition are also frequently produced. 



Protosulphate of iron is insoluble in alcohol, soluble in twice its 

 weight of cold water, but much more so in hot water. When heated 

 it loses six equivalents of its water of crystallisation, at a red heat is 

 deconi]K>sed into sulphurous and sulphuric acids, which escape, while 

 peroxide of iron (colcothar) remains. It is largely used in black 1 > 

 and in the manufacture of writing INK. 



2. Pennlphateofiron(Fe.,O i ,SSOJ. Five parts of crystals of proto- 

 Ittlphate are dissolved in water, one part of sulphuric acid add. 

 nitric acid poured into the hot solution till no more black colour is pro- 

 duced. Abundance of nitrous vapours are evolved, and the yellow 

 solution, on evaporation to dryness, yields a buff-coloured mass of 

 persulphate of iron, having the above composition. 



This salt occurs native. [Inou, Coquimbile, in NAT. HIST. Div.] 



Potauio-tuJphatc of iron (t'v.O,, SSO, + KO, SO, + 24 Aq.) is a double 

 salt containing persulphate of iron and sulphate of potash. Correspond- 

 ing salts with the other alkaline sulphates may also be formed. They all 

 crystallise, and, being iaomorphous with common alum, are frequently, 

 though erroneously, called iron alums. They are formed by the spon- 

 taneous evaporation of mixed solutions of the salts, are to some extent 

 used in medicine, but are liable to decompose. 



The iodate, bromoJe, and jtercJilorate of iron are indefinite, unim- 

 portant salts. 



'et of iron. The protoxitrale (FeO, NO.) ia formed when cold 

 nitric acid is saturated with protosulphide of iron : on evaporating 

 the solution in vacuo, the salt crystallises out in pale green crystals 

 containing seven atoms of water. The crystals are very deliquescent, and 

 unstable. The pernitrate is produced when metallic iron ia dissolved 

 in strong nitric acid. It is very difficult to crystalline, the solution on 

 evaporation depositing a basic salt. Solution of pernitrato of iron is 

 used in dyeing. 



x.lirata of iron. Many of these occur native. [Ino.v, in NAT. 

 HIST. Dtv.j 



Anenilet and artenalet of iron. In cases of poisoning by arsenic the 

 best antidote to administer is freshly precipitated peroxide of iron 

 mixed with a little hydrate of magnesia. The efficiency of this anti- 

 dote dejwnds upon tho formation of pcrargenitc of iron, which ia an 

 insoluble compound ; that is, insoluble in water, but not altogether 

 insoluble in the liquids of the stomach, which usually contain traces of 

 c acids : the solution may, however be 



. .1 by mixing the oxide with magnesia, which neutralises those 

 acids in a fat more effectual manner than excess of peroxide of iron 

 would do. 



'ate* of iron. [ACKTATE.] 



<lallatet and tannatct of inn. [Lv K : Wrillny Int.] 



Citralet of iron. A double citrate of iron and ammonia is obtained 



frchly precipitated protoxide of iron is dissolved in citric acid 

 and exce** of ammonia added. The compound does not crystallite 

 but when the solution i* evaporated to the consistence of syrup and 

 pread over glass plates it drie* up and forms brilliant trausiarent 

 cales of garnet-red colour. 



of iron ami qmnine is a medicinal agent of some repute It 

 is pr. pared by dissolving together three part* of citrate of iron and one 



'i' : >'"' scaling as just described. The citrate <.i 



by saturating citric add with moist peroxide of iron . 

 rating and so, i , , inm iue by double dc, 



of sulphate of quinine and citrate of soda. 



Txrtratc of iron. A double compound of tortrate of iron and potauh 

 of somewhat similar physical properties to the last preparations, but 



