Decembek 8, 1905.] 



SCIENCE. 



751 



esting than the arrangement usually followed. 



Interlarded with the elements are the sepa- 

 rate headings for chemical, physical and 

 mathematical constants, for instance: An- 

 alysis, solutions, acoiTstic, electric, optical and 

 critical constants, logarithms and antiloga- 

 rithms. The table of atomic weights is based 

 on the values, published by the international 

 committee for 1905. 



In some of these cases it might have been 

 better to combine such headings as ' Barom- 

 eter,' ' Gases ' (with reduction of barometric 

 readings) and ' Air ' — or ' Freezing Mixtures,' 

 ' Temperature Measurement,' ' Thermochem- 

 istry ' and ' Heat Constants,' instead of having 

 each in a different part of the book. There 

 are, however, a large number of cross refer- 

 ences and an excellent index to facilitate its 

 use. 



In these chapters on constants the authors 

 have added some text, containing definitions, 

 derivations and explanations of the more im- 

 portant formulse, and frequent valuable refer- 

 ences to the literature. The chapter on 

 ' Units ' is the weakest part, since several mis- 

 takes and many loose statements have crept in 

 which should not occur in a book of this kind. 

 The gram is defined as the weight of one cubic 

 centimeter of water at 4° C, instead of the 

 concrete unit; density and specific gravity are 

 used as synonyms. While the numerical 

 values may be identical, namely, if we adopt 

 as unit volume the milliliter, or the wrong 

 definition of the gram (as mass) given by the 

 authors, the two names have not the same 

 physical meaning. The metric equivalent of 

 the English yard is given incorrectly and as 

 the two units of capacity in the United States 

 we find the gallon and the cask, the latter to 

 equal 121.1296 liters. The reviewer feels con- 

 fident that with him many readers of Science 

 are ignorant of the existence of such a unit, 

 though certainly one of this size might exist 

 in addition to the many others. The bushel, 

 however, is not given. It would have been 

 well to add to the metric horsepower, as used 

 in Germany, the equivalent of the English 

 horsepower. The electrical units have not 

 been defined in accordance with international 



agreement or with the values legalized in 

 Germany ; that the E.M.E. of a Clark standard 

 cell is given as 0.69735 volt — the reciprocal of 

 its actual value — may be an oversight. 



A distinction, though by no means clear, 

 seems to be made between ' Masse,' ' Gewicht ' 

 and ' Schwere,' the second probably corre- 

 sponding in meaning to Holman's ' Weightal,' 

 i. e.j, the quantity of substance as measured 

 by weighing; but the use of the first two as 

 synonyms and the statement that the gram- 

 weight is one of the units of the c.g.s, system 

 (see also: One Joule = 0.1019 mkg.) leads 

 finally to an evaluation of the ' weight ' of the 

 sun instead of its mass. 



While the reviewer may appear over-par- 

 ticular in such questions, it can not be suffi- 

 ciently emphasized how harmful mistakes of 

 this kind are. Like a fog in an otherwise 

 beautiful landscape, they have led many a man 

 ofl^ the right road. But this book is prin- 

 cipally intended for those who have passed 

 the danger point or are not concerned with 

 definitions of this kind, and for such it will 

 prove to be very useful on account of its handy 

 size and the good selection of the material. 



K. E. GUTHE. 



State University of Iowa. 



Die heterogenen Gleichgeiuichte vom Stand- 

 punhte der Phasenlehre. By H. W. 

 Bakhuis Koozeboom. Zweites Heft: Sys- 

 teme aus zwei Komponenten. Erster Teil. 

 14 X 22 em. ; pp. xii + 465. Braunschweig, 

 Friedrich Vieweg und Sohn. 1904. 

 In this volume the author discusses equi- 

 librium phenomena for two-component systems 

 in which only the components can occur as 

 solid phases. Compounds and solid solutions 

 are to be considered in a later volume. Mix- 

 tures of gases apparently do not come under 

 the scope of the book and the author starts off 

 with the equilibrium between liquid and vapor. 

 We have the boiling-point curves for mix- 

 tures which give neither a maximum nor a 

 minimum boiling-point, for pairs of liquids 

 with a constant maximum boiling-point, and 

 for pairs of liquids with a constant minimum 

 boiling-point. We also have the pressure-con- 



