▪ I. rhodium1
(ˈrəʊdɪəm)
[mod.L. (sc. lignum wood), neut. of rhodius rose-like (f. Gr. ῥόδον rose), which has been sometimes associated with Rhodius Rhodian.]
1. rhodium-wood [partial translation of mod.L. lignum rhodium; cf. rhodian-wood], the sweet-scented wood of two species of Convolvulus, C. floridus and C. scoparius, of the Canary Islands.
| 1661 Culpepper London Disp. 7/3 Wood of..Rhodium encreases milk in Nurses. 1741 Compl. Fam.-Piece i. iv. 249 Take..Rhodium Wood, Yellow Saunders, each 6 Drams. |
2. oil of rhodium [
= mod.L.
oleum rhodii]: oil obtained from rhodium-wood; rosewood oil.
| 1678 Phillips, Lignum Rhodium, or Aspalathus, a certain sweet Wood; of which, the Oyl of Rhodium much used in Perfumes is made. 1764 Museum Rust. I. 397 To the above-mentioned means of alluring by trailing..is added another of very material efficacy, which is, the use of oil of Rhodium. 1844 H. Stephens Bk. Farm III. 1296 A mixture of wheaten-flour and sugar..flavoured with the oil of rhodium. 1846 J. Baxter Libr. Pract. Agric. (ed. 4) II. 371 To entice Rats. Oil of Rhodium, twenty drops [etc.]. |
▪ II. rhodium2 Chem. (
ˈrəʊdɪəm)
[f. Gr. ῥόδον rose + -ium.] a. A very hard white metal of the platinum group, discovered by Wollaston (see
quot. 1804). Symbol Rh, formerly Ro.
| 1804 Wollaston in Phil. Trans. XCIV. 419, I design in the present Memoir to prove the existence..of another metal, hitherto unknown, which may not improperly be distinguished by the name of Rhodium, from the rose-colour of a dilute solution of the salts containing it. 1836 T. Thomson Min., Geol., etc. II. 460 Rhodium is a white metal, of so difficult fusion, that hitherto it has been obtained only in grains. 1880 E. Cleminshaw Wurtz' Atom. Theory 223 Iridium and rhodium..form well-characterised trichlorides and sesquioxides. |
b. attrib., as
rhodium plating,
rhodium-plated adj. (hence
rhodium-plate vb. trans.);
rhodium salt;
rhodium-black (see
quot.);
rhodium-gold, native gold containing rhodium; so
rhodium ingot;
rhodium pen, a steel pen tipped with rhodium.
| 1883 Jrnl. Chem. Soc. 849 *Rhodium black, obtained by the action of formic acid on rhodium hexchloride and sodium chloride. |
| 1868 Watts Dict. Chem., *Rhodium-gold. 1882 Dana Min. 110 A rhodium-gold from Mexico. |
| 1895 Daily News 2 May 3/1 A *rhodium ingot. |
| 1839 Ure Dict. Arts, etc. 1068 The inalterable nibs of the so-named *rhodium pens. |
| 1962 L. S. Sasieni Optical Dispensing i. 4 A very satisfactory alternative way of producing a frame with a white finish is to *rhodium-plate a yellow gold filled frame. |
| Ibid. vii. 170 A *rhodium-plated or gold-filled supra. 1971 Flying Apr. 112/3 (Advt.), Pilots Sunglasses. Air Force style rhodium plated adjustable metal frame. 1978 Neiman-Marcus Christmas Bk. 29 The glitter of rectangular cut crystals, hand-set in rhodium-plated 2{pp} bar pins. |
| 1950 Thorpe's Dict. Appl. Chem. (ed. 4) X. 539/1 *Rhodium plating baths have come into extensive use during the past 20 years for producing a non-tarnishing finish on silverware and on electrical-contact materials. 1962 L. S. Sasieni Optical Dispensing i. 23 The effect of a white gold filled frame is often produced by rhodium-plating. |
| 1853 W. Gregory Inorg. Chem. 261 The *rhodium salt [is] insoluble in alcohol. |