IRIDIUM

(Lat.), n. n. Ia(e)-ri"d'ia-usm(u4m). From Tpi?, the rainbow. Fr, i. Ger, /. It., Sp., iridio. A metallic element discovered by Tennant in 1804. It is found in nature a ociated with osmium and platinum. It is a white, lustrous, brittle metal, almost infusible, and heavier than platinum, having the sp. gr. of 22'38. It may also be obtained as a porous ma called spongy i., and as a very fine black powder called j. black. In composition it acts as a trivalent radicle, forming iridioiiK salts, and as a quadriva- (Fr). See /. dioxide. Bisulfure d'i. (Fr). See /. disulphide. Chlorure d'i. (Fr). See 1. chloride. I. arsenate. Fr, arseniate d'i. Ger., arsensaures I. A salt of i. and arsenic acid, a brown precipitate formed on adding sodium arsenate to i. chloride, and heating. [B, 2.] I. bromide. Fr, bromure d'i. Ger, I'bromur (1st def.), I'bromid (2d clef.). 1. See /. tri bromide. 2. See 7. tetra bromide. I. chloride. Fr., chlorure d'i. Ger, I'chloriir (1st def.), I'chlorid (2d def.). 1. See I. Mchloride. 2. See 7. tetrachloride. I. dioxide. Fr, dioxyde d'i., bioxyde d'i. Ger., I'oxyd. A black powder, IrO, insoluble in acids. [B, 3; B, 158, 270(o, 38).] I. disulphide. Fr, bisulfure d'i. Ger, rmilfid. A black powder, IrS2. [B, 3.] I. hydrate, I. hydroxide. Fr, hydrate d'i. Ger., I'hydrat. 1. I. sesquihydroxide, or irido-iridic hydroxide. 2. I. tetra hydroxide. I. iodide. Fr, iodure d'i. Ger., I'jodid. See 7. tetra iodide. I. mono sulphide. Fr,nioosulfure d'i. Ger., I's ulfur. A compound of i. and sulphur, IrS. [B. 3.J I. nitrite. Fr, azotite d'i., nitrite d'i. Ger., I'nitrit, salpetrigsaurefi I. A body, Irs(NO9)g, entering into the formation of the iridio-nitrites. [B.] I. oxide. Fr, oxyde d'i. Ger., I'oxydul (1st def.), I'oxyd (2d def.). 1. See 7. sesquioxide. 2. See I. dioxide. I'oxydhydrat (Ger). See 7. tetra hydroxide. I'oxydul (Ger). See 7. sesquioxide. I'oxydulhydrat (Ger). See 7. xesquihydroxide. I. sesquibromide. Fr, sesquibromure d'i. See 7. tri bromide. I. sesquichloride. Fr, sesquichlorure d'i. See 7. trichloride. I. sesquihydroxide. Ger., 7 sesquihydroryd, I'oxydulhydrat. More properly, i. tri hydroxide, a yellowish-green substance, Ir.,(OH)4; according to others, a black powder insoluble in acids, but having a violet modified form soluble in certain acids. fB, 3: B, 270 (a, 38).] I. sesquioxide. Fr.,sesquioxyde d'i. Ger., I's esquioxyd. Irido-iridic oxide, IrO3, a bluish-black powder formed by heating i. in the air, and decomposed again by raising the temperature to 800 C. [B. 3.] I. sesquisulphide. Fr., sesquisidfure d'i. Irido-iridic sulphide; a brown powder, Ir3S3. IB, 3.] I. sulphide. Fr, sulftire d'i. See 7. mono sulphide, I. sesquisulphide, and 7. disidphide. I. sulphite. Fr., sulfite d'i. Ger, schweflignaures I'oxydid. Irido-iridic sulphite, Ira(SOs}3 + 6HaO. It forms yellow crystals. [B, 3.] I. tetra bromide. Fr, tetra bro mure d'i. Ger., I'bromid. Iridic bromide, a blue, crystalline substance. IrBr4. With hydrobromic acid it forms bromiridic acid, and with trie bromides of other metals double salts, called irid i bromides. fB.] I. tetrachloride. Fr., tetrachlorure d'i. Ger, I'chlorid. Iridic chloride, a substance, IrCl4. With hydrochloric acid it forms chloriridic acid, and with the chlorides of other metals double salts called iridiehlorides. [B, 3.] -I. tetra hydroxide. Ger, I'oxydhydrat. A substance, Ir(OH)4, having the color of indigo. [B, 3.] I. tetra iodide. Fr., tetraiodure d'i. Ger, I'jodid. Iridic iodide, a black powder, Irlv [B, 3.] I. tri bromide. Fr., tribromure d'i. Ger. I'bromiir. Iridious bromide, a substance, Ir3BrB + 8HUO, occurring in olive-green crystals. With the bromides of other elements and radicles it forms compound salts called iridiobromides. [B. 3.] I. trichloride. Fr., trichlorure d'i. Ger., I'chloriir. Iridious chloride, an olive-green substance, IrCl, forming, with the chlorides of other elements or radicles, double salts called iricliochlorides. [B, 3.] I. tri hydroxide. See 7. sex qui hydroxide. Monosulfure d'i. (Fr). See 7. mono sulphide. Oxyde d'i. (Fr.). See 7. o-nrfe. SHi vt HligRaurea I'oxydul (Ger.). See 7. sulphite. Sesquielilorur' d'i. (Fr). See 7. trichloride. Sesquioxyde d'i. (Fr.). See 7..wqtuoride. Sesquisulfure d'i. (Fr. ). See 7. Kcxqitisitlphide. Sulflte d'i. (Fr). See 7. sulphite. Sulfure d'i. (Fr). See 7. sulphide. [s. 486]