Recent Books ~ f f ~ c tofs Ions i n Colloidal Systems. Dr. l,sonon M ~ C ~ A B L I Williams S. & Wilkins co.,Baltimore, Md.. 1925 108 pp. 18 5 X 12.5 cm. 62.00. This hook is a short summary of a series of that were delivered in several during the In ail there are eight short chapter. in t h e 108 paper, dealing with such subject. as adsorption in general, elecfrokineticphenomena. origin of t h e electrical double layer, anomalies of charcoal, coagulation. Donnan membrane equilibrium, and i y o t r o p i ~ionuences. The treatment is entirely qualitative thraughout, and were i t not for t h e peculiar style of expression i t would make profitable reading for an hour or two. The following sentence, for example, is submitted ss evidence of t h e preceding statement: "May I be allowed t o recall t h e fact t h a t we measure t h e absolute zero point of a mereurv electrode by investigating the conditions lor t h e maximum of ourface tension of a mercury meniscus, and. alter ail we know about this problem, this determination of t h e absolute value of the potential of mercury from a surface phenomena may he applied for t h e potential of the mercmy which forms one pole of a galvanic chain, too: provided t h e surface tension is measured against such solutions which contain no strongly adsorbable ions." There are, however,numerourideas in the work t h a t make t h e book worthwhile for t h e special worker in this field. This is especially true of the commenteon t h e Donnan equilibrium and is riro well illustrated by the following pithy statement; "The Gibb3 theory of ad3orption which deals only with surface tension har proved itself as practiezliy rather fruitlesr and sometim- misleading." The most glaring error in t h e book io t h e repeafed statement t h a t charcoal is t h e only substnnee capable of adsorbing capillary active non-eleetmlyten from solution. This point is greatly stressed in t h e chapter on charcoal, and its refutation would decrease t h e importance of t h e conclusions as drawn. Such an erporition as presented in this iittle book of Professor Michaelis is valuable i n so far as i t emphasizes t h e need of fundamental investigation 01a ~ e r i o u sand careful nature in this field. For i t certainiy may he raid with great emphasis t h a t the problems of ion adsorption are a t prerent largely unsolved Indeed t h e author himself sums u p t h e situation most admirably as follows: " I t seems t h a t in order to arrive a t a satisfactory solution of this mobirm one should start from ~
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quite new fundamental supporitiaos. I n the meantime we have t o p u t u p with the qualitative considerntioos given above:' W. A. P*Tarcx Distillation i n h a s t i s e .
C. E u r o r r .
Nostrand C o . N. Y.. 1925. xi 41 fi"'Fs and *'.OO net'
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D. V& 188 PP.
This is a companion hook t o "Distillation Principles" by t h e same author and a knowledge of t h e principles of t h e vaporization of liquids is asaumed. The chapters are: simple distillation. fractionation. discontinuous fractionation, continuous fractionation, fractional eondenration, heat transfer, apparatus, ethyl alcohol, pctroleum, and coal tar. The author doe. n o t hestitate t o use mathematics where i t is needed and there are maoy such places. I n the first part general formulae are developed which are let- applied t o specific ca3er. T h a e nre a considerable number of reference t o t h e literature of dirtillation. The treatment of each topic is logical and the e p pianations and illurtratioll~ are sufficient but there is no excess. The material is packed somewhat daneiy andrequirenattemtitiertitidiig. However, one who is not willing t o d o t h a t kind of reading had better avoid this subject. The book in for t h e student who is looking forward t o practical work and for the practical man who is stiii a student and is trying t o improve his methods and apparatus. It does not umtain ready-made formulae and deeigus for all occssionr but rather aims t o help t h e student to help himself by pointing out t h e fundamentals and indicating ways of applying them. Considerable information ir given about actual practice in distillation. The illustrations are ail diagrams or sectional drawings. Such sketcher show much more about design and operation than d o pictures of plants. A notable feature in t h a t attention is constantly called t o gaps in our knowledge and t o t h e d c
