384 



NA TURE 



[August 17, 1905 



into the simpler units of the amorphous state ; and, 

 further, that the water molecules of a crystal may by the 

 same agency be broken away from their combination with 

 the salt molecules. Since the publication of the earlier of 

 these observations Prof. Spring has shown that the acid 

 sulphates of the alkali metals may be mechanically decom- 

 posed into two portions, one of which contains more acid, 

 and the other more base than the original salt. It is 

 important to recognise that in these three apparently short 

 steps the transition has been made from the overcoming 

 of the simple cohesion of similar molecules in contact with 

 each other to the breaking asunder of the chemical union 

 of dissimilar molecules. At each step the solid molecules 

 appear, not as mere ethereal abstractions, but as sub- 

 stantial portions of matter which can be touched and 

 handled mechanically. 



The physical properties of a gas are primarily due to its 

 being an assemblage of rapidly moving molecules. These 

 simpler and more general properties can coe.\ist with, and 

 may be modified by, the more complex relations introduced 

 by chemical affinity as it occurs in compound gases and 

 mixtures. 



It appears to me quite legitimate similarly to regard the 

 physical properties of a liquid as due to its being an as- 

 semblage of rapidly moving molecules. The liquid system 

 is highly condensed, and the motions of its molecules are 

 controlled by the cohesive as well as by the repulsive 

 forces. The closer approximation of the molecules may 

 reduce their mean free path to an extremely small amount, 

 or it may even cause their translatory motion to disappear, 

 so that the whole kinetic energy of the liquid molecules 

 may be in the form of rotation or vibration. 



As we can imagine a perfect gas, so also may we 

 imagine a perfect liquid, the physical properties of which 

 are as simply related to the laws of dynamics as are those 

 of the gas. But the conditions of the liquid state being 

 also those most favourable to the play of chemical affinity, 

 the internal equilibrium of solutions or of mixed liquids 

 must be a resultant of this affinity together with the 

 primary forces of the ideal liquid state. 



An ideally perfect solution — that is, a solution the 

 physical properties of which are determined solely by tiie 

 number of molecules it contains in a given volume — must 

 consist of a solvent and a solute which have no chemical 

 affinity for each other, so that their molecules will neither 

 associate nor dissociate in solution. Probably only com- 

 paratively few solutions will be found which even ap- 

 proximate to this ideal perfection. But it appears to me 

 that the study of the problems of the liquid and the dis- 

 solved states may be much simplified by the recognition 

 (i) that the primary physical properties of liquids and 

 solutions are due to the fact that thev are assemblages of 

 molecules endowed with the amount and the kind of kinetic 

 energy which is proper to their temperature ; and (2) that 

 as these primary physical properties of the liquid and dis- 

 solved states may be masked and interfered with by 

 chemical affinity, they should be studied as far as possible 

 in examples where the influence of this force is either 

 absent or at a minimum. 



NOTES. 

 \\*E regret to learn of the death, at the age of seventy- 

 eight, of Dr. T. R. Thal^n, professor of physics at the 

 University of Upsala, and one of the most eminent Sw'edish 

 men of science. The Rumford medal was awarded to him 

 by the Royal .Society for his researches on spectrum 

 analysis, and a gold medal was awarded to him by the 

 .Swedish Association of Ironmasters in 1874 for his in- 

 vestigations of njagnetic iron ore deposits. 



A Reuter telegram from Berlin states that the Inter- 

 national Conference for the Investigation of Earthquakes 

 met on Tuesday at - the Ministry of the Interior, under 

 the (Presidency of Privy Councillor Dr. Lewald. All the 

 States which possess organised staffs for the investigation 

 of earthquakes were invited by the German Government 



NO. 1868, VOL. 72] 



to take part in the conference. The conference is expected 

 to last two days. 



The Government Eclipse Expedition in charge of Sir 

 Norman Lockycr, K.C.B., has arrived at Palma, Balearic 

 Islands, where the instruments will be erected for observ- 

 ations of the total solar eclipse on August 30. A Reuter 

 telegram from Madrid reports that the telegraph authori- 

 ties have decided to frank all telegrams dispatched by 

 members of the various astronomical expeditions regarding 

 observations of the eclipse. 



The London County Council has erected a memorial 

 tablet on No. 14 Hertford Street, Park Lane, where 

 Edward Jenner, the originator of vaccination, resided in 

 1S03 ; and also on No. 34 Gloucester Square, Hyde Park, 

 where Robert Stephenson, the engineer, resided at one 

 time. 



The death is announced of the Rev. Dr. J. Keith. He 

 was one of the leading educationists of the north of Scot- 

 land, and took an active interest in scientific pursuits, 

 especially botany. 



The Times correspondent at Wellington, N.Z., states 

 that the Postmaster-General hopes, with the cooperation 

 of Australia, to have wireless telegraphy established across 

 the Tasman Sea within twelve months. The cost will be 

 28,000!. 



The meeting of the tenth International Navigation 

 Congress will be held at Milan from September 24-30. 

 Particulars can be obtained from the secretary, M. 

 Dufourny, 38 Rue de Louvain, Brussels, or from M. 

 Saujast Di Tculada, Villa Real, Milan. 



Mr. W. E. L.-vngdon, formerly telegraph superintendent 

 and chief of the electrical department of the Midland 

 Railway, died on Saturday last, .August 12. He was for 

 many years a member of the Institution of Electrical 

 Engineers, and was president for the session of 1901-2. 



Profs. RUbert Boyce .wd Ronald Ross, of the Liver- 

 pool School of Tropical Medicine, left Liverpool en Satur- 

 day by the Campania for New York. They are proceeding 

 to New Orleans, their services having been offered to the 

 authorities in connection with the outbreak of yellow 

 fever at that port. 



A Reuter message from Hong Kong, dated August 12, 

 reports that for nine hours a continuous series of earth- 

 quake shocks, two of them prolonged, have been felt at 

 Macao. Slight shocks have been experienced in Hong 

 Kong. An earthquake shock was felt at Chamonix on 

 August 13, at 10.30 a.m. The usual subterranean rumbling 

 noise was he;ird. 



Mr. Ger.\ld Dudgeon has been appointed by the 

 Secretary of State for the Colonies to e.xamine and report 

 upon questions relating to the development of the agri- 

 cultural resources (including cotton) of British West Africa. 

 His title is Superintendent of .Agriculture for the British 

 West .African Colonies and Protectorates. 



The weather report issued by the Meteorological Office 

 for the week ending August 12 shows that in all the 

 eleven districts into which the British Islands are divided 

 the rainfall since the beginning of the year is below the 

 average, except in the north of Scotland, where the excess 

 is 52 inches. The deficiency amounts to 46 inches in 

 the north-east of England, and to 30 inches in the Midland 

 counties. While at the end of the week in question nearly 

 the whole ot England and Ireland were under the influence 



