ttl 



II'KCUANIC At ID. 



IRON. 



Another ort of ipecacuan is obtained from the Piych'itria emetica, 

 called striated ; thin kind contains only 9 per cent, of emetina, aiul the 

 undulated or amylaceous ipecaouan, the produce of the Itirtianbuuia 

 cobra, holdi only 6 per cent, of emetina, with 92 per cent, of starch. 

 Beside* then, the root* of numerous other plants are used in tropical 

 countries u emetics, and often termed ipecacuan. 



The du*t or powder of ipecacuau applied to any mucous surface 

 causes irritation and increased secretion from the part. It i- 

 employed to excite the stomach either' to augmented secretion or to 

 invert it* action, and effect vomiting. It U also capable, by 

 combined with other substances, of being directed to the skin, ana 

 producing increased perspiration. When given in very small doees, it 

 improve* the appetite and digestive powers ; in a somewhat larger doee, 

 it acts on the intestine* ; but in n .-till larger, it invert* the action of 

 the stomach, and Oceanians vuaiiting. It may therefore be used in a 

 great many disassen, ouch as indigestion, dysentery, rheumatism, 

 common colds, croup, Ac. [ KVII.TA ; EMETICS ; DIAPHORETICS ; ANTI- 

 DOTE*.] 



Some caution is requisite in using it, especially with children, aa 

 it has a great tendency to produce sleep, and deep depression some- 

 times follows its use. When an emetic action is required, powder 

 having a nauseous odour in preferable, ; when a diaphoretic action is 

 desired, as at the commencement of a common cold, ten or fifeeen 

 drops of ipecacuan wine ore proper, out of any mild warm drink. 



In case of violent vomiting from an over-dose, infusion of strong tea 

 or oak bark may be given, and a mustard poultice applied to each side 

 : :i. juak 



IPECl'ANU ACID (C,.H,,O 14 r). An acid of doubtful composition, 

 found in the root of the t'i/>haflu ipecacuanha. It U amorphous, red- 

 brown, and very bitter. It gives a green colouration with penal ta of 

 iron, and a violet-black with ammonia. 



U'oM.KA ITKUA. [JALAP.] 



IPOMIC ACID. [SKBACIC Acm] 



IRIDKSCKNCK. A term applied to those brilliant colours which 

 appear on substances presented in very thin plates, such as the soap- 

 bubble, the lamina: of mother-of-pearl, &c. [IXTKIII KIIKXL-K.] 



IHIDIUCYAMMiKX (IrC.N.) is a hypothetical compound radical. 

 It forms with hydrogen iridiocyanic acid or hydroiridiocyanic acid, and 

 with potassium an iridiocyauide of potassium. The latter occurs in 

 the form of colourless crystals, and gives a deep indigo blue with the 

 salts of peroxide of iron. This is one of the many compounds of a 

 metal with cyanogen, like ferrocyanogen, and which have all the power 

 of combining with other metals possessed by that body. Thus there are 

 cobaltocyanogen, chromocyanogen, platinocyanogen, &c. [Cl^. 



IKIDIUM (In. An elementary metal occurring in certain ores of 

 platinum. [PLATINUM, in NAT. HIST. Drv.] It was discovered in 

 1804 by Tennaut, but has since been more minutely examined by 

 MM. Deville and Debray. The following is the method recommended 

 by those cheuiixts for the extraction of iridium from the otln-r metals 

 with which in nature it is always associated. The impure chloroiridiate 

 of ammonia obtained in the preparation of the metal mil 

 [RUTHENIUM] u dried and calcined, and the resulting powder subjected 

 to a stream of hydrogen, whereby all traces of chlorine anS oxygen 

 are removed. Platinum and some osmium are now extracted by aqua 

 regia, and ruthenium separated by fusion with nitre and caustic potash, 

 the alkaline salts being dissolved out by water. Any osmium th.it 

 remains may be dissipated by the oxidising flame of the blowpipe, and 

 thepure iridium fused in the oxy hydrogen lime furnace. 



The colour of iridium is pure white, somewhat resembling polished 

 steel At the ordinary temperature it is scarcely malleable, but at a 

 bright white beat it is perfectly so. The specific gravity of iridium is 

 21-15; its equivalent, 08-66. In the pure state it is unacted upon 

 by acids. 



Iridium, and oxygen combine in three different proportions forming 



Protoxide of iridium IrO 



Hetquloxide of Iridium Ir.O. 



Binoxids of iridium IrO, 



The pro/arid* is a black powder obtained on decomposing tin- dry 

 nrotochloride with solution of potash. It is difficultly soluble in acids, 

 tat it rapidly attacked by alkalies. The / : ..,,,,,-d when 



the finely divided metal is ignited in n current of air ; it is a bluish- 

 black powder. The binojridt is, according to Clauss, always ] 

 tated as an indigo-coloured hydrate when either <>f the chlorides of 

 iridium is boiled with an alkali. 



Iriiliam anil auljthur form combinations corresponding to the oxides, 

 and may be obtained by passing sulphured. .1 hydrogen t! 

 toons of the rcapccUve oxides in acids. The pnto$ulj>kide (IrSi i* 

 yellowish brown, the xtyuitulphide (It S,) brown-black, the bi>- 

 (Ir Sj). like the protosulphide, but darker. 



' unds : 



Pn! "/,,. (Ir Cl is formed on passing chlorine gas 



MIII heated to incipient redness. It is a dark 



olive-green powder, insoluble in water, and but sparingly soluble in 

 acids, but when fused with potash and the resulting oxide dissolved in 

 hydrochloric acid and evaporated to dryneiis, the prot<.chloride remains 

 "" I! u ni !T ren , t y eUow ?" "<% olble in hot water. 



OetgntfUondt of iridium sublimes when the 6nely divided metal is 



strongly ignited in current of chlorine. In this state it is insoluble 

 in water. !>iit when prejiaredby oxidising iridium with fu- 

 digfmthlg the residue in hydrochloric acid, then l"im- with v 

 red-brown solution. 



Hi'-hloride uf iridium (IrCl,) results when chlorine gas is passed 

 through water in which >te of ammonia is diffused. With 



alkaline and other salts bichloride of iridium forms doul.l 

 corresponding in < to the analogous platinum compounds. 



Iridium and carl m. \\ In n metallic iridium is held in tin' tlauiv of 

 a spirit lamp, a soft, dark gray p-v, ..n its surface, owing to 



the ]>enetration of carbon from the spirit into the metal 



Iridium forms combinations with photphanu and iodine; its oxides 

 also form taltt with some oxygen acids, but the resulting compounds 

 have been little -in, lied. 



/ridium-tilitcl; having ijualities very similar to platinum-black, ig 

 precipitated on boiling an alcoholic solution of bii-ulphate of iridium. 



The alluyi of iridium produced in a well fused state by the ei 

 ment of the oxyhydrogen lime-furnace described by M M 

 Debray ('Annales de Chimie et de Physique" for August, 1859) 

 possess properties that reuder them exceedingly v.i carts. 



Thus the platinum alloy, containing 21-3 per cent. of iridium, is 

 perfectly malleable, and may be worked into vessels possessing greater 

 rigidity than if constructed of platinum alone. Such vessels, more- 

 over, are quite unacted upon by acids, and the operation of dissolving 

 platinum in aqua regia may be conducted in them without risk of 

 their surface being acted upon. 



The derivation of the word Iridium is from Ira, the rainbow, being 

 suggested by the many tints assumed by solutions of the oxides of 

 this metal. 



I1MD1UM-BLACK. [IBIDIUM.] 



IRIS. [RAINBOW.] 



IRITIS is an inflammation of the iris, the membrane that 

 surrounds the pupil of the eye. [EYE, in NAT. lli-r. Hiv.] It most 



uly originates in a disordered stat 



syphilis, but it sometimes follows the exposure of the eye t.. an i- 

 light, or is produced by external injury, as the wound which is made 

 in the operation for cataract, &c. 



Iritis is principally characterised by an effusion of lymph, both into 

 the substance of the membrane, producing a peculiar dullnes- 

 colour, and on its surface iu the form of small masses which adhere at 

 the edge of and around the pupil. The eye is at the name time irritable 

 to light, and the pupil is closely contracted ; tin, ,,f the 



conjunctiva, and a zone of a bright pink colour is usually seen 

 surrounding the margin of the cornea. 



Iritis is very likely to end in adhesions of the iris to the adjacent 

 parts, by the lymph which is deposited upon it becoming organised, 

 and having its vessels united with theirs ; in which case, irregularity 

 iu the form of the pupil, a loss of its pow- n acting and 



dilating, or even its complete closure and obliteration, with corres- 

 ponding degrees of obscurity of vision r total blindne.-.-. m;i\ 

 These results may be produced in a few days ; and- the treatment 

 must therefore be prompt and vigorous, lil". .1 .-hould I,,- drawn 

 by cupping or leeches from the head or neck ; mercury is usually 

 administered in frequent and full doses till salivation is pro- 

 duced, and belladonna should be applied to or around the eye, 

 to produce dilatation of the pupil and thus prevent its being 



IRON, Medical Propertict of. Iron, in a purely metallic state, docs 

 not exert any appreciable influence over the human syst< 

 theleas metallic iron is recommended as an antidote to poisoning by 

 the salts of copper. Iron filings have been administered with a view 

 to precipitate the copper in a metallic and therefore innocuous state. 

 White of egg is a 1 1 . i .le antidote. 



The employment of iron filings to absorb foetid exhalation- tiom the 

 feetislessbeneiKi.il than that, of recently prepared and freshly pow- 

 dered charcoal, put every morning into the shoes of those atllictcd with 

 this annoyance. Iron tilings are sometimes prescribed medieinallv. but 

 before any marked effect can be produced by t In m, t he metal must become 

 an oxide or a salt; the presence of any acid in the stomach or alimentary 

 canal promotes this change, while alkalies ret ml it. This form has 

 been adopted iu the treatment of worms, chiefly from the notion that 

 the worms would be annoyed and dislodged by the m< 

 of particles of iron. This is an erroneous view. . rics.] 



Tincture of sesquichloride of iron in infusion of quassia i 

 ben. -licial in all canes of worms, but its efficiun .in its tonic 



and astringent pro|>erties. 



irationx and uses of iron, 



Sesquioxide of iron ^ rust, or the subcarbonate of sonn oicias), 



has been given i" tie douloureux, in very large dose* ; in some instances 

 with success. It is likewise useful in some cases of spasmodic con- 

 tractions of the joints. The very large doses in which it is required to 

 be given u a serious impediment to its use ; for n 

 averse to it, but it clogs the intestines, which require to 1 

 cleared out by a brisk cathartic. It is less objected to when given 

 in London porter, a very suitable vehicle. 



The black oxide is not so liable to objection, as it is more readily 

 soluble in the fluids of the alimentary canal 



Ammonio-chloride of iron possesses no advantage over the simple 



