subject. It is to be hoped that others will write on the practical applications of - physical chemistry in a similar manner. Physico-Chcmicd Geology -~ presupposes a knowledge of the fundamentals of geology and mineralogy, but none of the phase rule. I n consequence the first two chapters deal with heterogeneous equilibrium in general, thermal analysis and a detailed discussion of one., two-, and threecomponent systems. These chapters are very well done, hut i t seems that i t might have been more profitable to presuppose a knowledge of these matters and devote the space saved to a more detailed discussion of the various problems considered. The chapter on Isomorphism and Solid Solution is very h e and abounds in geological illustrations. The same is true of the chapters on Polymorphism, The Igneous Rocks. Mineral Formation, Metamorphism, The Salt Deposits, Ore Deposits, and Refractories and Abrasives. One could wish for a much more extended discussion of Colloids in Geology. The Physical Chemistry of Rock Weathering would he improved by stressing mass action effectsto a greater extent. This book is non-mathematical and full of interest even for one not well up in geology and mineralogy. It reads easily and incites a desire to know more. The chief criticism to be made is that Dr. Rastall did not keep on with his narrative. M. HARWG MALCOLM ~
Old Chemistries. EDGAR F. SMITH,University of Pennsylvania. McGraw-Hill Book Company, Inc., New York, 1927. x 89 pp. 32 illustrations. 11.8 X 17.5 cm. $2.50.
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The main purpose of this book, accord-
ing to the author, is to bring to the attention of chemists, in particular to American chemists, "a story of chemical books used for instructional purposes in the infancy of our country." The author, as is well known, is the leading historian of chemistry in America; and from his large and splendid collection of old books he has selected those volumes which best illustrate the fact that "the American Fathers of Chemistry had an interest in their science equal to that exhibited by any of its modern disciples." From a perusal of "Old Chemistries" we learn what foreign influences prevailed in the teaching of chemistry to our ancestors; also the part early American chemistry teachers had in the writing of textbooks. The books selected cover a period of about three hundred years, beginning in the middle of the sixteenth century. The illustrations are excellent, and they include portraits of such eminent men as Benjamin Rush, Lavoisier, Joseph Black, Robert Hare, and Benjamin Silliman. The volume indudes a portrait oI a n e Marcet who wrote a most delightful text, entitled "Conversations on Chemistry." This book first aDpeared in London about 1805. In this very interesting volume, Dr. Smith clearly exhibits his thorough knowledge of the history of the science he loves so well, and in his story shows us that-"through these manifold, twinkling, sparkling pages something of the past beckons us, whispers us, delights us." "Old Chemistries" would be a valuable addition to any library, and should be of special interest to educators and chemists who want authoritative information concerning the history of one of the greatest sciences. WILLIAMFOSTER
