l62 



NATURE 



[May I, 1919 



The third volume presents in an easily acces- 

 sible form the most important theoretical and 

 practical work on the quantum hypothesis, em- 

 bracing- much that is not included in Jeans's report. 

 We have noted one awkward slip, a "howler" 

 on p. 27 in the proof that the central force is 

 equal to mv^j p. The angle between tangent and 

 secant is made equal to the angle at the centre, 

 and then by an abuse of infinitesimal g-eometry 

 the correct answer is obtained. In chap, v., on the 

 structure of the atom, we are surprised to find 

 Moseley's worl? dismissed in less than a page, the 

 same space nevertheless being allocated to Allen's 

 empirical relation, while Barkla is not mentioned. 

 There is a misprint in the second formula on 

 p. 115. We sincerely deprecate the habit of be- 

 stowing double-barrelled names on equations save 

 when there is clear evidence of independent dis- 

 covery. From the text-book it would appear that 

 the " Marcelin-Rice " equation (p. 139) was dis- 

 covered by Marcelin, and the method of deduction 

 improved by Rice. If this is the case the second 

 name should be dropped from the equation. \Nt 

 should have liked to see the appendices (of which 

 i. and ii. are by J. Rice) incorporated in the text. 



We have confined our attention almost entirely 

 to the additions and alterations made by the 

 author in his new edition. If we have emphasised 

 the defects rather than the excellences of his 

 work, we must plead that we are seeking to help 

 him in the presentation of ' the only complete 

 system of physical chemistry by an English-speak- 

 ing author. We have no hesitation in saying that 

 we regard these volumes as absolutely indis- 

 pensable books of reference to every advanced 

 worker in physical chemistry and chemical physics, 

 though it is unfortunate from the point of view 

 of a standard text-book that the author's treat- 

 ment of the newer portions of his subject will 

 compel him to make frequent changes in subse- 

 quent editions. A.M. W. 



ACIDOSIS. 

 The Principles of Acidosis and Clinical Methods 

 for its Study. By A. Watson Sellards. Pp. 

 vi-hii7. (Cambridge, Mass.: Harvard Uni- 

 versity Press, 1917.) Price 45. net. 

 ACIDOSIS may be defined as a condition in 

 which there is a diminution in the normal 

 slight alkalinity of the blood or tissues of a living 

 organism ; and a real or suppK>sed state of acidosis 

 has come in recent times to play a leading part in 

 the explanation of many abnormal symptoms, 

 including in particular a number of those which 

 have been produced in the course of the war. The 

 whole subject is thus one of considerable present 

 scientific interest, and for this reason Dr. 

 Sellards's book on the principles of acidosis is 

 specially welcome. 



The fact that in the living body the faintly 

 alkaline reaction of the blood and tissues is regu- 

 lated in a remarkable manner has been known for 

 long. The non-volatile acid or alkali produced 

 NO. 2583, VOL. 103] 



within, or introduced into, the body varies con- 

 siderably, according to the composition of the 

 food ; and in man acid predominates, mainly on 

 account of the fact that the alkali contained in 

 the food is not sufficient to neutralise the sulphuric 

 and phosphoric acids produced in the oxidation of 

 proteins. The excess of inorganic acid is partly 

 got rid of by the secretion of an acid urine, and 

 partly neutralised by the formation of ammonia ; 

 while organic acids introduced into or formed 

 within the body are for the most part oxidised 

 along with other organic materials, the resulting 

 carbonic acid being got rid of in respiration. It 

 is only in recent years, however, that it has been 

 shown that the concentration of free carbonic acid 

 in the blood is regulated by the breathing with 

 extreme delicacy, and that the breathing is 

 itself normally regulated by the very minute 

 changes in hydrogen-ion concentration produced 

 by variations in the concentration of free carbonic 

 acid in the blood, or by variations in its hydrogen- 

 ion concentration from other causes. 



The lungs thus constitute a safety valve which 

 acts more freely or less freely according as the 

 hydrogen-ion concentration of the blood increases 

 or diminishes. We can correlate the variation in 

 respiratory activity, first, with the variations in 

 concentration of CO2 in the air of the lung alveoli, 

 and consequently of the free carbonic acid in the 

 arterial blood ; secondly, with the corresponding 

 variations in hydrogen-ion concentration of the 

 arterial blood. The result of this correlation has 

 been to show that the regulation of hydrogen- 

 ion concentration in the blood of man is 

 so delicate that existing methods of measurement 

 are far too coarse to reveal the changes 

 in reaction to which the breathing reacts, 

 unless where there are very great variations in 

 the breathing. Thus with the existing methods 

 of measurement the hydrogen-ion concentration 

 of the blood appears to be constant ; and where 

 apparent distinct variations have been found they 

 have nearly always been due to faulty methods of 

 measurement. Minute variations in hydrogen-ion 

 concentration are constantly occurring, as shown 

 by variations in the breathing, but, as a rule, they 

 are too small to be directly measurable by existing 

 methods. There Is also evidence that extremely 

 small variations in hydrogen-ion concentration are 

 of very great physiological importance. 



Unfortunately, these considerations have not as 

 yet been fully realised by medical men, or by more 

 than a few physiologists, and the result is a verit- 

 able pandemonium of doctrine and practice in 

 connection with real or supposed acidosis and its 

 treatment. Dr. Sellards's book is not free from 

 the prevailing confusion, as he seriously misinter- 

 prets the connection between breathing and the 

 hydrogen-ion concentration of the blood. His 

 book is, nevertheless, valuable and very well 

 written. He rightly lays stress on the fact 

 that, except in the extremest cases, accurate 

 measurements show no variations in the hydrogen- 

 ion concentration of the blood. But he proceeds 

 to conclude that no variations exist even in Avhat 



