Volume 1
Watts' dictionary of chemistry / revised and entirely rewritten by H. Forster Morley and M.M. Pattison Muir ; assisted by eminent contributors.
- Date:
- 1888-1894
Licence: Public Domain Mark
Credit: Watts' dictionary of chemistry / revised and entirely rewritten by H. Forster Morley and M.M. Pattison Muir ; assisted by eminent contributors. Source: Wellcome Collection.
Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.
680/796 (page 654)
![c CACAO v. Theobromine. CACODYL v. p. 318. CACOSTRYCHNINE O21H22N5O,0. A product of the action of HN03 on strychnine (q. v.). Golden needles (from dilute HN03) or hexagonal plates (from cone. HClAq). SI. sol. most menstrua, sol. alkalis, forming red solutions.— B'2H,PtCl6 (Claus a. Glassner, B. 14, 773). CACOTHELINE C^H^NA,. A product of the action of HN03 on brucine (q. v.). Orange laminae (containing aq). Weak base; sol. alkalis, v. si. sol. hot water, insol. alcohol and ether.—B'BaO 7aq.—B'.,H2PtCl(i (Strecker, A. 91, 76; C. R. 39, 52 ; Rosengarten, A. 65, 111; Claus a. Rohre, B. 14, 765). CADAVERIC ALKALOIDS v. Ptomaines. CADET'S FUMING LIQUID v. p. 318. CADMIUM. Cd. At. w. 111-7. Mol. w. 111-7 ; gaseous molecule is monatomic. [320°] (Person, A. Ch. [3] 27, 250; Rudberg, P. 71, 460; v. Riemsdyk, C. N. 20, 32). (763°-772°) (Carnelley a. Williams, C. J. 33, 284). S.G. (molten) 8*65, (hammered) 8-8 (Stromeyer, S. 22, 362 ; Schroder, P. 106, 226; 107, 113; Matthiessen, P. 110, 21, &c). V.D. 55-8 (Deville a. Troost, C. R. 52, 920). S.H. (0°-100°) •0548 (Bunsen, P. 141, 1), -0567 (Regnault, A. Ch. [3] 26, 268). C.E. (linear, 0°-100°) •003323; (cubical for 1°) -000094 (Kopp, A. 81, 32; Matthiessen, P. 130, 50; Fizeau, C. B. 68, 1125). T.C. (Ag = 100) 20-06 (Lorenz, W. 13, 422). E.C. (Hg at 0° = 1) at 0°, 13-46 ; at 100°, 9-5 (Lorenz, W. 13, 422 a. 582). Heat of fusion 13,660 (Person, P. 76, 426). S.V.S. abt. 12-8. Emission-spectrum characterised by lines 3609-6, 3465-4, 2747-7, 2572-2, 2313-6, 2288-9 (Hartley, T. 1884. 63). Cd was discovered by Stromeyer in 1817 in a specimen of zinc carbonate (<S. 21, 297; 22, 362; v. also Hermann, G. A. 59, 95). The name cadmium was derived ivom cadmia fossilis by which name zinc ore was then known. Occurrence.—With Zn in various native sul- phides, carbonates, and silicates, especially in the Silesian zinc ores (v. Damour, J. pr. 13, 354; Stadler, J. pr. 91, 359; Blum, J. 1858. 734 ; Bunsen, A. 133, 108). CdS occurs nearly pure as Greenockite at Bishopton in Renfrew- shire. Formation.—In the distillation of crude zinc oxide with charcoal; the greater part of the Cd distils over before the Zn. Preparation. — ZnO containing CdO, or metallic Zn containing Cd, is dissolved in dilute H,S04Aq or HClAq; the warm solution is satura- ted with H,S; the CdS thoroughly washed and dissolved in cone. HClAq; most of the free HC1 is removed by warming, the solution is diluted and filtered, and an excess of (NH4)2C03 is added; the pp. of CdC03 is well washed, dried, and strongly heated; the CdO thus produced is mixed with ^ 0f its weight of pure powdered charcoal and heated in a retort of hard-glass or porcelain when pure Cd distils over (Stromeyer, S. 22, 362). Properties.—White with slight blue tinge ; very lustrous; soft, but harder than zinc; very malleable, ductile, and flexible ; more tenacious than tin ; crystallises easily in monometric forms, chiefly the octahedron (v. Eammerer, B. 7, 1724; also G. Rose, P. 85, 293). Vapour is yellow. Cd does not decompose water even at 100°; but if Cd vapour and steam are passed through a hot tube the steam is decomposed (Regnault, A. Ch. 62, 351). Cd oxidises slowly on the surface by exposure to air ; when heated in air it burns to CdO. The atomic weight of Cd has been determined (1) by finding the V.D. of, and by analysing, CdBr2 (Meyer, B. 12,1292 ; Dumas, A. Ch. [3] 55,158; Huntington,P. Am. A. 17, 28) ; analyses of CdG,04 (Lenssen, J. pr. 79, 281); reduction of CdSO, to CdS (v. Hauer, C. C. 1857. 897) ; analyses of CdO (Stromeyer, S. 22, 366); (2) by determining the S.H. of Cd (Bunsen, P. 141, 1; Regnault, A. Ch. [3] 26, 268); (3) by comparing, as regards crystalline form and general reactions, salts of Cd with salts of Zn, Be, Mg, and Hg. In the gaseous mole- cule CdBr2 (this is the only compound of Cd whose V.D. has been determined) the atom of Cd is divalent. The gaseous molecule of Cd is monatomic. Cd is a distinctly metallic element; it acts on HClAq, H,SO.,Aq, &c, evolving H and forming salts of the form CdX2 where X2 = Cl2, Br2, S04, C03, &c.; many of these salts combine with the similar salts of the more positive metals (K, Ca, Mg, &c.) to form double salts; but few basic salts of Cd are known, the most marked are derived from such weak acids as H2Cr04, H3BO.,, &c. No compound of Cd exhibits any acidic functions. Cd02H, acts to- wards acids as a salt-forming hydroxide ; its heat of neutralisation by H,S04Aq is about the same as that of the corresponding hydroxide of Mn, Ni, Co, Fe, or Zn, [Cd02H-Aq, H2SO'Aq] = 23,824 (v. Th. 1, 339 a. 436). Cd02H2 is de- hydrated by heat; the oxide CdO is not converted to Cd02H2 by direct addition of H20. Cadmium is closely related to Zn, it is less positive than that metal; it is also related to Mg on one hand and to Hg on the other (v. Magnesium group or elements). Reactions.—1. Heated in air, or O, CdO is produced. — 2. Heated nearly to redness in bromine, CdBr2 is formed.—3. Aqueous solu- tions of hydrochloric, sulphuric, or nitric, acids are decomposed by Cd with formation of chloride, sulphate, or nitrate of the metal.—4. Heated with S02Aq to 200° CdS is formed (Geittner, A. 129, 3*54); possibly sulphite and thiosulphate are first formed (v. Schweitzer, C. N. 23, 293 ; Fordos a. Gelis, A. 50, 260). Combinations.—Most compounds of Cd are formed from the oxide or other salt. Cd com- bines directly with the elements O, CI, Br, I, P, S, Se, Te, and with many metals (v. Cadmium, oxide op, &c, and Cadmium, allots of). Detection and Estimation. — Formation of the yellow sulphide, CdS, insoluble in dilute HClAq and also in solution of ammonium sul- phide, characterises Cd salts. Cd is usually estimated by ppn. as CdC03 (by K2C03Aq), the pp. is strongly heated, and the CdO is weighed. Separation from other metals may be effected](https://iiif.wellcomecollection.org/image/b21995990_0001_0680.jp2/full/800%2C/0/default.jpg)
