452 



NATURE 



[June 9, 192 1 



account of the abnormality it displays in so many 

 particulars. It is well known that the temperature 

 of maximum density of water is lowered by pres- 

 sure, a fact which was established by Tait in 1883, 

 and, later, by Amagat, and confirmed on theoreti- 

 cal grounds by van der Waals and Puschl. Each 

 increment of i atmosphere pressure lowers the 

 temperature of maximum density by 00217° C. 

 The influence of pressure on the melting-point of 

 ice is equally well known, and has been frequently 

 studied since it was first pointed out by James 

 Thomson and his brother. Lord Kelvin, in 1849, 

 and its natural effect traced by Faraday and 

 Tyndall in the phenomenon of regelation and the 

 movement of glaciers. The large body of evi- 

 dence on the relation of pressure to melting-point 

 has been carefully collected and displayed in 

 tabular form. For its discussion we must refer 

 to the work itself. 



A considerable section of the work is devoted 

 to a consideration of the influence of pressure 

 upon the flow and permanent increase of density 

 of solid substances, and upon the viscosity of 

 liquids. As regards water, the viscosity dimin- 

 ishes with increasing pressure up to 900 atmo- 

 spheres, between 0° and 32° C, when it attains a 

 minimum. Above this temperature it increases 

 by pressure; below it it decreases in proportion 

 to the increase of pressure. All the phenomena 

 of the compressibility of water serve to confirm 

 the general belief that it is an associated liquid 

 — i.e. its molecular complexity under ordinary 

 natural conditions is not properly represented by 

 the simple formula HgO. 



Space will not permit of more than the briefest 

 possible reference to the remaining sections of 

 this valuable work. These treat of the influence 

 of pressure on the electric conductivity of solu- 

 tions and solids ; on the thermo-electric properties 

 of metals; on dielectric constants; on the 

 validity of Faraday's first law; on solubility, 

 diffusion, refractive index, and polarimetry. 



It will be seen from this account that the work 

 is mainly concerned with the influence of pressure 

 upon the physical properties of substances, and to 

 that extent its title is rather a misnomer. It 

 might, perhaps, be more fittingly styled piezo- 

 physics. However, the border-line between 

 physics and chemistry is becoming more and more 

 ill-defined, for the spheres of the two sciences 

 gradually merge into each other. There is some 

 point in the good-natured gibe that chemistry, 

 after all, is only the dirty part of physics. We 

 may, however, express the hope that the authors 

 will add to our obligation by extending their work 

 NO. 2693, VOL. 107] 



so as to include the influence of pressure upon 

 chemical change. There is now a fairly abundant 

 literature upon the subject, but it requires to be 

 collected, annotated, and digested, and its general 

 principles elucidated. T. E. Thorpe. 



Social Degeneration. 



(i) Social Decay and Regeneration. By R. Austin 

 Freeman. With an introduction by Havelock 

 Ellis. Pp. XX -t- 345. (London: Constable and 

 Co., Ltd., 1921.) 185. 



(2) The History of Social Development. By Dr. 

 F. Miiller-Lyer, Translated by Elizabeth Coote 

 Lake and H. A. Lake. With an introduction 

 by Prof. L. T. Hobhouse and Prof. E. J. 

 Urwick. (Studies in Economics and Political 

 Science.) Pp. 362. (London : George Allen 

 and Unwin, Ltd., 1920.) 18s. net. 



(1) QAMUEL BUTLER tells us that the 

 »^ Erewhonians destroyed all their 

 machines and lived happily ever after. An 

 Erewhonian financier pointed to the "magnificent 

 ruins of the railway-station " as an object of in- 

 terest in his park, Mr. Austin Freeman, in all 

 seriousness, agrees with the Erewhonians. His 

 book is a searching indictment of the machine as 

 the cause of our present discontents. 



Ill fares the land, to hastening ills a prey, 

 Where wealth accumulates and men decay. 



The decay wrought by machinery is not 

 numerical ; it is something much worse. 

 The ultimate factor of national decline is 

 racial deterioration ; and in modern societies 

 this is very extensive and pernicious. Un- 

 favourable variations are not eliminated, and 

 there is a reversed natural selection in favour of 

 the unfit. The essential character of modern 

 civilisation is a war of mechanism on man. 



" Mechanism has destroyed industry and replaced 

 it by mere labour ; it has degraded and vulgarised 

 the works of man ; it has destroyed social unity 

 and replaced it by social disintegration and class 

 antagonism to an extent which directly threatens 

 civilisation ; it has injuriously affected the struc- 

 tural type of society by developing its organisa- 

 tion at the expense of the individual ; it has en- 

 dowed the inferior man with political power 

 which he employs to the common disadvantage 

 by creating political institutions of a socially de- 

 structive type ; and finally, by its reactions on the 

 activities of war, it constitutes an agent for the 

 wholesale physical destruction of man and his 

 works and the extinction of human culture. It 

 is thus strictly analogous to those anti-bodies by 



