292 



NATURE 



[May 5, 1910 



depend on the physical qualities of the solvent, but on some 

 chemical relationship between solvent and solute. It was 

 suggested by the author that water, acting as an ampho- 

 teric electrolyte, could form a salt when mixed either with 

 a strong acid or with a strong base, and that the high 

 conductivity of mixtures of sulphuric acid and water, and 

 the slight conductivity of mixtures of formic acid and 

 water, were due neither to free acid nor to free water, 

 but to the presence of an oxonium sulphate or formate in 

 the liquid. The absence of conducting power in mixtures 

 of water with hydrogen cyanide or formamide was 

 attributed to the weakness of their acidic and basic quali- 

 ties and the impossibility of combining them with water 

 to form a salt-like electrolyte. 



Prof. Gu\e, in a paper " On the nature of molecular 

 associations in the special case of water," referred to a 

 new formula by which the coefficient of association of a 

 liquid might be deduced from its molecular surface energy, 

 and showed that in the case of water at the boiling point 

 it gave the factor 1-96 — a value considerably lower than 

 that (2-66) deduced by Ramsay and Shields, but agreeing 

 closely with a value (1-98) deduced by Walden by another 

 method. He also described the results of a calculation 

 whereby the degree of association of liquid water could be 

 calculated from the degree of association of steam on the 

 assumption that the law of mass-action held good in both 

 ■>;asesi and that the value of the constant remained the 

 same- throughout. Takin-g the figure 1-089 given by Bose 

 for the association-factor of steam, the value 1-99 deduced 

 for water was shown to agree satisfactorily with those 

 derived by the other methods referred to above. 



The values given by Prof. Guye for the coefficient of 

 association of water at 100° were, in the subsequent dis- 

 cussion, referred to by Mr. Bousfield, who pointed out that 

 (if correct) they would render untenable Sutherland's theory 

 that liquid water is a- binary mixture of trihydrol and 

 dihydrol, since even at 100° it would be necessary to assume 

 the presence of considerable amounts of monohydrol in 

 order to reduce the (average) association-factor below 2. 



The paper by Mr. W. R. Bousfield and Dr. T. M. 

 Lowry, on " Liquid Water a Ternary Mixture. Solution- 

 volumes in Aqueous Solutions," was an extension to other 

 solutes of some curious observations made five years 

 previously in the case of aqueous solutions of caustic soda. 

 The solution-volumes of the soda were found to vary 

 largely with the concentration and with the temperature, 

 the most remarkable feature of the variations being the 

 occurrence of a maximum of solution-volume at about 

 60° C. in liquids of all concentrations. The gradual con- 

 version of the ordinary, slightly concave, expansion curve 

 into a strongly convex curve had now been traced through 

 a seri€s of solutes — chloral hydrate, sugar, acetic acid, 

 silver nitrate, potassium, sodium, calcium and lithium 

 chlorides. The curves for caustic soda were shown to be 

 intermediate between those for sodium and calcium 

 chlorides, and to form one member of a series of pro- 

 gressively changing types. The drooping of the ends of 

 the curves was shown to depend on the occurrence during 

 the preparation of the solutions of a contraction resulting 

 from the formation of hydrates. Such a contraction 

 indicates that water is increased in density by combining 

 with a solute ; in order to give definiteness to this concep- 

 tion, th^ suggestion was made that the density of com- 

 bined water is similar to that of its denser constituent 

 (dihydrol) in the free state, and that the contraction on 

 dissolution is due mainly to the conversion into hydrate of 

 lighter constituents present in the liquid. As this contrac- 

 tion in the case of lithium chloride solutions increases both 

 above and below 40°, it follows that a lighter form of 

 water is produced, not only by cooling, but also by heat- 

 ing it. . The presence, of three constituents in the liquid 

 (ice, water and steam, or trihydrol, dihydrol and mono- 

 hydrol) is indeed absolutely necessar\' in order to account 

 for the complex changes of volume that have been observed 

 in water and in the solutions prepared from it. 



Mr. Sutherland's paper " On the constitution of water " 

 had been circulated before the meeting, and owing to lack of 

 time was taken as read. His suggestion that the hexagonal 

 symmetry of ice cr\-stals may be taken as evidence in favour 

 of the " trih3'drol " formula will now receive more serious 

 consideration than would have been the case a few years 

 ago ; although his method of deducing the relative sizes 



NO. 21 14, VOL. 83I 



of the atoms differs from that made use of by Barlow and 

 Pope, and his method of " packing " is not the " closest " 

 possible, there is no doubt that the general scheme of 

 the arrangement is sound, and that the argument from 

 crystal structure to chemical constitution may now b'- 

 accepted as both legitimate and useful. Unlike the previous 

 authors, Mr. Sutherland considers that monohydrol doi s 

 not exist in liquid water, but is present in all salts contain- 

 ing water of crystallisation. He attributes to it a density 

 (1-31 in the solid and 1-26 in the liquid state) considerably 

 greater than that of dihydrol (1-13 and 1-09) or of trihydrol 

 (092 and 0-88), and in an appendix gives values for a 

 number of its other physical properties. 



Prof. Nernst's paper on the specific heat of ice, water 

 and steam was read by Dr. Wilsmore. The survey covered 

 the whole field from —200° to the highest temperatures, 

 but attention was directed specially to minima in the specific 

 heat of water vapour under moderate pressures and of 

 liquid water at moderate temperatures ; both minima were 

 attributed to the dissociation of complex molecules. The 

 question of specific heats was also dealt with in a note on 

 the specific heat of water of crystallisation by Mr. F. P. 

 Sexton, of Truro, which was read by Dr. J. A. Harker. 

 In the case of copper sulphate the first four molecules of 

 combined water were found to have a specific heat 0-499, 

 whilst the fifth molecule gave the value 0-508. Mr. Bous- 

 field pointed out that the value 0-5 also held good for the 

 combined water in solutions of potassium chloride, the 

 heat capacities of which could be calculated correctly by 

 assuming them to be mixtures of free water, hydrate-water, 

 and salt. Dr. Senter pointed out that the values now 

 given agreed well with the view, in support of which much 

 evidence was available, that in compounds such as copper 

 sulphate four molecules of water were definitely associated 

 with the metallic atom, the remainder being perhaps 

 attached to the molecule as a whole. 



Early in the evening Mr. H. B. Baker showed a re- 

 markable experiment on the influence of purification in 

 retarding the action of water on sodium amalgam, the 

 underlying idea being that if water could by purification 

 be rendered non-conducting it might also be rendered 

 chemically inactive. Similar experiments on the inactivity 

 of highly purified nitric acid were described by Mr. Veley. 



A complimentary dinner, the first in the history of the 

 Faraday Society, was given in honour of its foreign guests. 

 Profs. Walden and Guye, on Wednesday, April 27, under 

 the chairmanship of the president, Mr. James Swinburne, 

 F.R.S. The English guests included Sir William Ramsay, 

 Sir William Tilden, Sir Joseph Larmor, Prof. H. B. Dixon, 

 Prof. Divers, and Dr. Chree. In responding to the toast 

 of the guests of the evening. Prof. Walden referred to the 

 scientific relationship between Russia and Great Britain, 

 remarking, incidentally, that the first Russian chemist was 

 an Englishman, sent by Queen Elizabeth to Russia in the 

 sixteenth century. Prof. Guye dwelt on the debt which 

 chemists all over the world owed to Faraday, and gave 

 an interesting account of Faraday's visit to Geneva when 

 he accompanied Sir Humphry Davy on his tour through 

 Europe. T. M. L. 



RECENT ADDITIONS TO IDEAS REGARDING 

 THE INTERNAL STRUCTURE OF THE 

 EARTH.' 

 "DEYOND the superficial observations made by geologists, 

 ^ not extending more than about one two-hundredth of 

 the radius below the surface, even by indirect means, we 

 are dependent on mathematicians for our ideas regarding 

 the physical state of the earth's interior; these ideas _ are 

 based on extrapolation from physical constants obtained 

 in the laboratory, and their variety extends to the number 

 of possible permutations and combinations of the three 

 physical states of matter — solid, liquid, and g.aseous. 

 Halley's conception of a core and shell rotating at difTerent 

 speeds has been revived by Sir F. J. Evans (1878) and 

 bv the distinguished founder of this series of lectures to 

 explain the secular variations of magnetism. The 

 Laplacian hypothesis, based on Clairault's theorem, is now 

 1 AbPt^art of the Wilde lecture delivered trv the Manchester I.iterarv and 

 Philosophical Society on March 22, by Sir Thomas H. Holland, K.C.I.E., 

 F.R.S. 



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