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.
692/796 (page 666)
![Absorbs 6NH3 (Isambert, C. B. 66,1259). Forms an easily decomposed double compound with Agl; CaI2.2AgI.6H20 (Simpson, Pr. 27, 120) Calcium hydroxyhydrosulphide v. post under Calcium sulphydbate. Calcium, Oxides of. Two oxides are known; CaO a strongly basic compound, and CaO, which acts as a peroxide. CaO, cannot be formed by the action of 0 on CaO (comp. BaO,). I. Calcium ^monoxide. CaO (Lime, burnt lime). Mol. w. unknown, as compound has not been gasified. S.G. 3-15 (Schroder, P. Jubelbd. 452); S.G. (crystalline, by heating Ca2N03) 3-251 (Briigelmann, W. 2,466; 4, 277). S. variable according to state of aggregation of the CaO &c. Lamy (A. Ch. [5] 14, 145) gives the following numbers representing grams of CaO in 1000 grams of solution; CaO being made (1) by heating Ca2N03, (2) by heating CaCOs, (3) by heating CaO,H,: — Temp. (l) (2) (.3) 0° 1-362 1-381 1-430 10 1-311 1-342 1-384 15 1-277 1-299 1-348 30 1142 1-162 1-195 45 0-996 1-005 1-033 60 0-844 0-868 0-885 100 0-562 0-576 0-584 H. F. [Ca, O] = 130,930; [Ca, O, Aq] = 149,260 (Th. 3, 251). Preparation.—Pure marble, or Iceland spar, is strongly heated in a crucible with a hole in the bottom to allow escape of CO,; or a piece of charcoal is placed in the crucible beneath the marble, CO is thus formed and sweeps out the CO, with it. CaC03 is not completely decom- posed when heated in an atmosphere of C02; v. calcium carbonate, under Carbonates. Sestini (Fr. 4, 51) strongly heats powdered marble with sugar, washes with H.,0, dissolves in HN03Aq, pps. CaC03 by (NH,)2 C03Aq, and strongly heats the dried pp. By strongly heating Ca2N03, in quantities of about 15-20 grams at a time, in a porcelain flask, Briigelmann (W. 2, 466 ; 4,277) obtained cubical crystals of CaO ; semitransparent, harder than the amorphous form, and less easily acted on by H20 and C02. Properties and Reactions.—White, amor- phous (or crystalline v. supra), powder : does not fuse at full white heat. Strongly basic ; reacts with most acids to form salts. CaO is decom- posed by heating to whiteness with K ; heated in CI, CaCl2 is formed. CaS is produced by heating with S, and CaS and CaC03 by heating in CS,. CaO does not combine with O (v. Conroy, C. J. [2] 11, 809). Combinations.—With carbon dioxide to form CaC03 (but dry CaO does not react with C02: Scheibler, B. 19, 1973); combination begins at about 400° (v. Birnbaum a. Mahn, B. 12, 1547); [CaO, 00^ = 42,520 (Th. 3, 251). Heated with silica or silicates, silicates of Ca are formed, which in contact with water set to a hard com- pact mass (hydraulic mortars). With water, Ca02H2 is formed with production of much heat [CaO, H'O] = 15,540 (Thomsen); the lime is said to be slaked. II. Calcium dioxide, Ca02 (Calcium per- oxide). Mol. w. unknown. Prepared by adding pure H202Aq to excess of CaOAq, or by adding excess of CaOAq to Na202Aq containing some HN03Aq ; collecting pp., washing well with cold water, and heating the Ca02.8H20 thus produced in a current of dry air free from CO, to 100° — 120°. Forms a snow-white crystalline powder; does not melt at red heat, but gives off O and forms CaO. The hydrate Ca02.8H20 is slightly soluble in H20, in contact with H20 it slowly decomposes to CaO,HAq and H; soluble in NH^ClAq, but not in NH3Aq ; dissolves easily in dilute acids, even in H.C2H30,Aq, without evolution of O. It forms prismatic dimetric crystals, isomorphous with BaO,.8H„0 and Sr02.8H,0 (Schone) (Thenard, A. Ch. [2] 8, 306; Conroy, C. J. [2] 11, 808; Schone, B. 6, 1172). Calcium oxide, hydrated, CaO,H2, v. Cal- cium, HYDROXIDE OF. Calcium, Oxybromide of, CaBr2.3Ca0.15H20. v. Calcium, bromide op ; Properties. Calcium, Oxychloride of, CaCl2.3Ca0.15H20, v. Calcium, chloride of ; Combinations, No. 4. Calcium, Oxysulphides of, v. Calcium poly- sulphides ; under Calcium, sulphides op. Calcium, Phosphide of. When Ca and P are heated under rock oil, and the unacted-on P is dissolved out by CS2, a black powder remains which is acted on by H20 and acids with pro- duction of PH3; this black powder is said by Vigier to be Ca phosphide (Bl. 1861. 5). By strongly heating CaO in P vapour, a brown, amorphous mass is obtained ; when heated with cone. HClAq, non-inflammable PH3 is evolved, but with dilute HClAq the gas evolved takes fire. Probably in the first case liquid PH2 is formed and at once decomposed to gaseous PH3 and solid P2H; in the second case the decomposi- tion of PH.2 proceeds more slowly, so that some is carried into the air with the PH3 and causes the combustion (Thenard, A. Ch. [3] 14, 12). The brown substance got by heating CaO in P vapour is said to be a mixture of CaP and Ca,P207 (Thtoard, I.e.) : this brown substance is described by Thenard as a very hard solid ; un- changed in dry air ; deliquescent in moist air ; burns when heated in air; acted on by water free from air gives CaOAq and PH2, PH,, decom- poses to PH3 and P2H, and the P2H is decom- posed by the CaOAq to Ca(H,PO,),Aq and H. Calcium, Salts of. Compounds obtained by replacing H of acids by Ca. These salts form one series CaX2 where X2=C12, (N03)2, SO.,, C03, § PO„ &o. They are generally formed by the action of CaO or Ca02H2 on the acids in aqueous solution, or by the decomposition of salts of the heavier metals by Ca02H2Aq. As none of the Ca salts has been gasified, the formulas are based partly on similarities between these salts and those of analogous metals which form gasifiable compounds, chiefly Zn, Cd, and Hg, and partly on the fact that the general formula CaX2 is the simplest that can be given, provided the atomic weight of Ca is about 40 (this has been established by analyses of CaCl2, CaC03 &c. and by determinations of the S.H. of the metal; v. Calcium). Salts of Ca derived from a great many acids are known; they are well marked stable bodies ; many form double salts; few basic salts are known. Most of the Ca salts are soluble in water ; the more insoluble are the arsenite, carbonate, fluoride, oxalate, phosphate, sulphate, and sulphite. With the exception of CaF2 all the salts are more or less](https://iiif.wellcomecollection.org/image/b21995990_0001_0692.jp2/full/800%2C/0/default.jpg)
