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.
710/796 (page 684)
![General formula and diameters of compounds. MO, M02, MS2, (SiO unknown, ? CS and C2S3) ; M03H2 (neither known except (?) in aqueous solution,'!;. Carbon and Silicon), 0S.,H2; MH4; C„H,,„+1, C„H2n, CnH2n_2, C„H,n_6, &c, &c, and a vast number of derivatives; MX, (X = C1, Br, I, or in case of Si also = F), M.,X6(X = C1, Br, or I where M = Si, X = C1 or Br where M = C), G,C14, C.,Br„ &c.; SiF6H ,; CH.,C1, CH..C1.,, CHC13, SiHCl,, SiHI3, &c.; C2N„ CNH and salts, CuN6FeH., and salts, C6N6FeH3 and salts, C5N5NOFeH2 and salts, &c, &c.; Si2N3 &o. The compounds of C and Si exhibit considerable differences in their jjroperties ; CO and C02are gases, Si02 is a very fixed solid; CS2 is a liquid, SiS2 a solid; CC14 is not acted on by- water, SiCl., is at once decomposed into Si02 and HC1; Si readily forms a fluoride and also a double fluoride with hydrogen, no corresponding compounds of C are known; CH4 is a stable gas, SiH, is oxidised by mere contact with air and is easily decomposed by heat (at 400°); Si (amorphous) dissolves in potash evolving hydro- gen and forming a silicate, carbon is unacted on by alkalis. Both elements form many com- pounds with H and 0 (alcohols, ethers, acids <feo.)) the composition of which is similar, in some cases the properties of the Si compounds closely resemble those of C, e.g. C(C.,H.,).,H and Si(C2H5)3H, C(C2H5)30H and Si(C,IL)3OH ; but in other cases the properties of the two classes of compounds differ much, e.g. CH3.C02H and C,H5.CO.,H are liquids soluble in water, but CH3.Si02H and C,H5.Si02H are amor- phous solids insoluble in water. Many sili- cates and carbonates are isomorphous. Sili- cates, except those of the alkali metals, are insoluble in water, and most of them are with difficulty decomposed by acids; the normal carbonates of the alkali metals are solu- ble in water, other normal carbonates are in- soluble ; aqueous solutions of acid carbonates are generally easily decomposed by heat yielding either normal or basic carbonates; the normal carbonates of the alkali metals are not decom- posed by heat alone, other normal carbonates are decomposed into metallic oxide and C02. Group IV. of the elements, as the elements are classified by the application of the periodic law, contains the following :— Even Odd 2 C 3 Si 4 Ti 5 Ge Series 6 8 Zr Ce 7 9 Sn 10 11 Pb 12 Th The metals titanium, zirconium, and germa- nium show considerable analogies with tin; cerium and thorium are usually classed toge- ther among the rarer earth-metals, and lead is generally considered apart from other metals : nevertheless there are well-marked analogies between all the elements which comprise Group IV. of the periodic system. Titanium is an amorphous body closely resembling amorphous silicon; it forms the compounds TiF„ TiCl„ TiBr„ Til.,, Ti2Cle, TiO„ (probably TiO(OH) and Ti(OH).,), Ti,03, Ti3N4, &e.; titanates are known (M2Ti03), many of them isomorphous with sili- cates and carbonates. Ti is more metallic than C or Si, it forms a sulphate Ti(SO,)2, and other salts wherein the hydrogen of acids is replaced by titanium. Zirconium again is more decidedly metallic than titanium ; it forms a series of well-marked salts Zr(SO.,)2, Zr4N03, &c, &o. On the other hand Zr resembles C and Si in that it has been obtained both as an amorphous powder, and also in crystals which resemble Si in their behaviour towards acids; zirconates (M2Zr03) are also known. Germanium forms oxides, chlorides, and sulphides, &c. (GeX and GeX2, X = 0 = S = Cl2), resembling those of Sn ; it Js, however, more markedly non-metallic in its chemical functions than Sn; physically Ge is decidedly metallic. Cerium forms two oxides Ce203 and Ce02; the former dissolves in acids forming a series of salts of which Ce23S04 is a type; Ce02 is a peroxide, it dissolves in HC1 with evolution of 01 and formation of CeCl2, but a sulphate Ce(S0,,), is known corresponding to the sulphates of Ti and Zr. Ce also forms a fluoride CeF„ a double fluoride 3KF.2CeF4, and a chloride Ce.XJl,;. Thorium again approaches more closely than cerium to Zr and Ti; it is a dark-coloured amorphous powder resembling Si, but more soluble in acids than Si, Zr, or Ti; it forms the compounds ThCl4, ThF4, K,ThF6, Th02, &c.; the sulphate is Th(SO,)2, and other analogous salts are known. Tin forms the two oxides and chlorides SnO and Sn02, SnCl2 and SnCl.,; the hydrates of Sn02 are feeble acids, producing stannates (M2Sn03) and metastan- nates (M2Sn501]), both of which are easily de- composed by dilute acids or by heat. Both the stannous salts e.g. SnS04, and the stannic salts e.g. Sn(SO,)2, are well-marked compounds. Lead is decidedly metallic in its character; it forms four oxides PbO, Pb304, Pb,03, and Pb02; the last is a peroxide, and it may also be re- garded as an anhydride inasmuch as plumbates (M,Pb03) exist, but these salts are very un- stable and easily decomposed. The best-marked salts of lead are derived from the oxide PbO, e.g. PbCl,, Pb2N03, PbSO„ &c.; PbCl4 has not been obtained pure, but this series of salts is represented by the tetramethide Pb(CH3)4 which is stable as a gas. The atoms of all the elements of Group IV., so far as evidence has been ob- tained, are tetravalent. Looking at the pro- perties of these elements as a whole, it may be said that carbon is to a considerable extent set apart from the others, but that it is more closely allied to silicon than to any other member of the group; that titanium and zirconium are closely related ; and that tin and lead, while showing distinct analogies with the rest of the group, are yet each characterised by properties which mark them off from the other elements. Not much can yet be said regarding cerium and thorium ; they require further study. For more details and descriptions of the various elements see the articles on these ele- ments ; also v. Titanium group of elements ; also v. Carbonates, Nitrates, Sulphates, &c. In some of their physical properties carbon and silicon, especially the latter, resemble boron, but boron must be classed with those elements the atoms of which are trivalent: v. Boron. M. M. P. M. CARBON C. At. w. 11-97. Mol. w. unknown ; element has not been gasified. S.G. diamond](https://iiif.wellcomecollection.org/image/b21995990_0001_0710.jp2/full/800%2C/0/default.jpg)
