i 2 6 CHEMISTRY 



Ha D D/s Hy Hp-H,! H v -H a 



Hydrogen 1.092 i . 100 1.115 1.122 0.023 0.029 



Oxygen, hydroxyl .. . 1.522 i-5 2 5 1-53* 1-541 0,006 0.015 



Oxygen, ether 1-639 *-643 1.649 1.662 0.012 0.019 



Oxygen, carbonyl . . . . . . 2.189 2.211 2.247 2.267 0.057 0.078 



Chlorine 5-933 5 967 6.043 6.101 0.107 0.168 



Bromine ......... 8.803 8.865 8.999 9-152 0.211 0.340 



Iodine 13-757 13 9 14 224 14.521 0.482 0.775 



Carbon (singly bound) 2.413 2.418 2.438 2.466 0.025 0.056 



Double linkage of carbon .... 1.686 1-733 1.824 1-893 0.138 0.200 



Triple linkage of carbon . . . . 2.328 2.398 2.506 2.538 0.139 0.171 



Nitrogen in primary aliphatic amines 2 . 309 2 . 322 2 . 368 2 . 397 o . 059 o . 086 



The view that liquid water, on the ground of its peculiar physical properties, is a 

 mixture of so-called "water-molecules" and "ice-molecules," the latter being more 

 complex but less dense, has lately been strengthened by the preparation of new varieties 

 of ice. When water at a pressure of about 3,000 atmospheres is cooled first to 80 C. 

 and then to 180 C., a specimen of clear ice is obtained which sinks in liquid air and is 

 therefore denser than ordinary ice, but which swells up and crumbles to the ordinary 

 variety when the temperature is allowed to rise to 130 (Tammann, Zeitsch. physikal. 

 Chem., 1910, "72, 609). More lately still, two new forms of ice have been described, 

 one of which appears only above o C. (Bridgman, Proc. Amer. Acad., 1912, 47, 441). 

 There is much to be said for another view that liquid water is a mixture of ice-molecules 

 HeOa, water-molecules H^, and steam-molecules H20, the relative proportion of these 

 varying with the temperature (Bousfield and Lowry, Trans., Faraday Soc., 1910, 6, 85). 

 According to Bose (Zeitsch. Elektrochem., 1908, 14, 269) even steam contains a certain 

 proportion of double molecules. 



The notable work of Morse and his co-workers on the osmotic pressure of sugar solu- 

 tions has lately been summarised (Amer. Chem. J., 1911, 45, 91, 237, 383, 517, 554; 1912, 

 48, 29). The ratio of osmotic pressure to gas pressure is constant for a given sucrose 

 solution between o and 25 and tends to increase slightly with the concentration 

 (reckoned in gm. mols. sucrose per 1000 gm. water) up to the value 1.114 for unit con- 

 centration. These results show conclusively that osmotic pressure is directly propor- 

 tional to the absolute temperature. The Earl of Berkeley's work on calcium ferrocyanide 

 solutions (Phil. Trans., A., 1909, 209, 177, 319) proves that the values of osmotic pres- 

 sure measured directly are in close agreement with the values deduced from the vapour 

 pressures of the solutions (compare E. B. xxv, 369 et seq., article " Solution "). 



New forms of apparatus for measuring osmotic pressure have been suggested by 

 Fouard (Compt. rend., 1911, 152, 519) and Trouton (Proc. Roy. Soc., A., 1912, 86, 149). 

 A noteworthy case of a natural membrane giving rise to osmotic effects is furnished by 

 the covering of certain barley grains (Brown, Proc. Roy. Soc., B., 1909, 81, 82). 



The view that hydrates exist in aqueous solutions is now accepted by the majority 

 of physical chemists, but opinion differs widely as to how far their composition can be 

 ascertained (see, for instance, Washburn, Tech. Quart., 1908, 21, 360; Jones, Amer. 

 Chem. J., 1909, 41, 10; Hudson, J. Amer. Chem. Soc., 1909, j/, 63; Rothmund, Zeitsch. 

 Physikal. Chem., 1909, 69, 523; Armstrong, Chem. News, 1911, 103, 97). An analogous 

 problem is presented by binary mixtures of organic liquids. The physical properties 

 of a mixture of two nominally indifferent liquids may differ considerably from what is 

 to be expected on the basis of the composition of the mixture and the corresponding 

 properties of the pure components (see, for instance, Faust, Zeitsch. physikal. Chem., 

 1912, 79, 97; Schulze, Zeitsch. Elektrochem., 1912, 18, 77). Such deviations may be 

 connected with the formation of a compound or with the association of similar molecules, 

 and some noteworthy attempts have been made recently to estimate quantitatively the 

 influence of these two factors in special cases (see Dolezalek, Zeitsch. physikal. Chem., 

 1908, 64, "ii"]; 1910, 7/, 191 ; Schulze, Physikal. Zeitsch., 1912, /j, 425). 



Much interest attaches to the study of organic liquids as ionising media. Of these, 

 formamide resembles water most closely; as shown by Walden, its solvent power is very 

 similar, its dielectric constant is somewhat greater than that of water, while potassium 



