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

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.

683/796 (page 657)

$correctly represented by the formula CclX._, where X = F, CI, Br, or I. The greater number of the salts of Cd are soluble in water ; the aqueous solutions redden blue litmus paper; they are poisonous. The haloid salts are not decom- posed by heat; salts of volatilisable acids give CdO when strongly heated. Many Cd salts are isomorphous with corresponding salts of Zn ; some, especially more complex double salts, are isomorphous with corresponding salts of Mg, Ni, Co, and Zn. A great many double salts containing CdX,(X = Cl,Br,I) are known; but few basic salts of Cd have been prepared. The principal Cd salts are borate ; bromate ; car- bonates ; chlorate, perchlorate; eliminate; cyanates, &c.; iodatc, periodatc; molybdate; nitrates, nitrites; phosphates, phosphite ; sclc- nates, selenitc; sulphates, sulphite, &c.; tung- state ; vanadate: v. Borates, Carbonates, &c. Cadmium, Selenide of. CdSe. Golden yellow, metal-like, crystalline, mass; by heating Cd in Se vapour; S.G. 8-79 (Strorneyer, S. 22, 362). The same body is said to be formed as a dark- brown pp. by passing H.,Se into solution of a Cd salt (Vigier, Bl. 1861. 5 ; Benault, C. R. 76, 283). Cadmium, Silicofluoride of. CdSiP,. Long, columnar, deliquescent crystals, obtained by action of H.,SiF,Aq on CdO (Berzelius, P. 1, 26). Cadmium, Sulphide of. CdS. Occurs native in hexagonal prisms (a:c = 1:-81257) as Green- ockite. Obtained as an amorphous yellow solid, by repeatedly heating to dull redness CdSO, in H.,S (v. Hauer, J. pr. 72, 338); by passing H,,S into a slightly acid solution of a Cd salt; by heating Cd with SO.,Aq (Geitner, A. 87, 31; Fordos a. Gelis, A. 50, 260; Schweitzer, C. N. 23, 293). Obtained also in crystalline form by fusing the amorphous CdS with K2COs and S (Schiiler, A. 87, 34); by heating CdCl, in H,S ; or by melting together CdS04, CaF„, and BaS (Troost a. Deville, C. B. 52, 920). CdS is also produced in crystals, but in small quantity, by passing S vapour over strongly heated CdO, or Cd (Follenius, Fr. 13, 411 ; Sidot, C. B. 62, 999). Crystalline CdS is non-volatile at any temperature ; it dissolves easily in boiling cone. HClAq, or dilute H2SO,Aq (Follenius, I.e.; Hofmann, A. 115, 286) ; S.G. 4-5, when melted 4-6. Sehiff (A. 115, 74) described CdSs as a yellow powder obtained by the action of K.2S5Aq on a neutral Cd salt in solution ; according to Follenius (Fr. 13, 411) this yellow solid is a mixture of CdS and S. Cadmium, Sulphocyanide of. Cd(CNS),. Ob- tained by action of HCNSAq on CdC03; v. Sulphocyanides, under Cyanides. Cadmium, Telluride of. CdTe. Black crys- tals, S.G. 6-20, by heating Cd with Te, and subliming the product in H (Margottet, C. B. 85, 1142). M. M. P. M. CADMIUM ETHIBE CdEt2. Obtained in impure condition from EtI and Cd. Takes fire in air (Wanklyn, C. J- 9, 193 ; Sonnenschein, J. pr. 67, 169). CESIUM. Cs. At. w. 132-7. [26°-27°] (Setterberg, A. 211, 100). S.G. i^0 1-88 (Setter- berg, i.e.). S.V.S. 70'7. Discovered by Bunsen and Kirchoff as chloride in the water of a mineral spring at Diirkheim (P. 113, 342). Vol. I. Name given because element characterised by two sky-blue (casius) lines in the spectrum. Occurrence. —Never free. Salts very widely distributed, but in very small quantities, along with Bb, chiefly as chloride and oxide ; in many minerals and mineral waters, in sea water and sea weed, in residues from saltpetre refining, in ash of tobacco, tea, coffee, and oak wood, &o. (v. especially Laspeyres, A. 134, 349 ; 138, 326 : also Smith, Am. S. [2] 49, 335 ; Erdmann, J. pr. 86, 377; Grandeau, C. R. 53, 1100; Lonstadt, C. N. 22, 25 a. 44). The rare mineral Polhu:, from Elba, according to analyses by Pisani, contains 34 p.c. Cs oxide combined with silica, and is free from Bb (A. 132, 31). Preparation.—1. The mother liquor, obtained by repeatedly evaporating the water of the mine- ral spring at Nanheim, and separating from the crystals which form, contains nearly ^ p.c. CsCl. Fe, Al, and the alkaline earth metals, are removed in the usual way ; the liquid is evapo- rated, and heated to volatilise ammonium salts added in the preceding processes ; the residue is dissolved in water and the Cs and Bb are ppd. as double chlorides of Cs, or Bb, and Pt, by addition of PtCl4Aq. The pp. is boiled in a very little water, and allowed to settle, the water is poured off while still hot; this process is repeated about 20 times, when the pp. will be quite free from K.PtCL and will consist of Cs„PtCl0 mixed with Bb.,PtCl0. The pp. is now reduced in H, CsCl and BbCl are dissolved out in boiling H.,0 (Bottger, J. pr. 91, 126). The mixed chlorides are converted into sulphates, these are dissolved in H.,0, BaOAq is added, BaS04 is removed by filtration, and the filtrate is evaporated to dryness in a silver dish after addition of (NH,)2CO:l; the residue is dried, dissolved in water, BaCOa removed by filtration, and twice as much H,.C4H40(i is added as is required to neutralise the solution of Cs2CO.( and Bb.,CO.(; the liquid is evaporated at 100° and crystallised; the pp. consists of CsH.C4H40,; mixed with BbH.C,H40,;. As the latter salt requires 8 times as much H.,0 as the former for solution, the two salts may be completely separated by fractional precipitation ; this pro- cess is continued until the crystals of Cs tartrate do not show a trace of Bb in the spectroscope (Bunsen, P. 119, 1; Allen, P. M. [4] 25, 189). By heating the tartrate, and dissolving the residue in H,S04Aq, and crystal- lising, Cs._.S04 may be prepared ; this is dissolved in H.,0, decomposed by BaOAq, ami the solution is filtered and evaporated to dryness in a silver dish, when CsOH is obtained. The CsOH is dissolved in absolute alcohol, and dry HCN is passed into this solution : CsCN is thus obtained as a white solid (Setterberg, A. 211, 100). A mixture of 4. parts CsCN and 1 partBa(CN)„ is heated just to melting in a porcelain crucible, and an electric current from 2 or 3 Bunsen cells is passed into the molten mass, in the manner described by Bunsen (P. 155, 633). The contents of the crucible are then warmed under petroleum when the metallic Cs melts into globules (Setterberg, A. 211,100).—2. The mixed chlorides of Cs and Bb, obtained as in 1, are converted into sul- phates, and then into alums by adding Al._,3S04Aq and evaporating. Bb alum is 4 times more soluble than Cs alum; Cs alum U U$