thread he finds in these charts with siderablyexpandedandimproved. Smits' their flow lines, which serve to connect theory of allotropy and the nature of the related subjects and persons. Marginal equilibria in intensively dried systems are references to British sovereigns and discussed briefly. American presidents help to fix periods One feels that the applications in of time. The veni comoleteness of metallor;raphy and peolom might profit- . -~ ~-

these charts is their sole drawback for ably be expanded somewhat. Also the there is so much material incorporated wisdom of dropping the chapter appearing in them that i t is difficult at times to follow the connection.

COLIN M. MACKALL

The Phase Rule and Its Applications. ALEXANDER FINDLAY, M.A., D.Sc., F.I.C., Professor of Chemistry, Uni- versity of Aberdeen. Longmans, Green & Co., New York and London, 1927. Sixth edition. xv + 326 pp. 165 illustrations. 21 X 14 em. $3.50 net.

Twenty-four years ago Professor Find- Lay wrote, "the desire having been to explain as clearly as possible the principles underlying the Phase Rule, and to illus- trate their application to the classification and investigation of equilibria, by means of a number of cases actually studied." He expressed also his desire to make the hwk elementary enough for the beginner while retaining such a thoroughness of treatment as to give him a really satis- factory foundation in the subject.

How well he has attained his object, the use of the hook by thousands of teachers abundantly attests. One planning to give a course in "Phase Rule" instinctively thinks of "Findlay" as his text. This sixth edition will still further confirm aU users in this thought.

Twenty-eight pages have been added since the fifth edition. This does not seem so much, but the real excellence of the new edition lies in the choice and arrangement of material. Many sec- tions have been entirely rearranged and rewritten, notably the sections on one- and two-component systems, with con- siderable increase in utility and clarity thereby. The practical applications of the subject have been stressed more than ever. The sections on reciprocal salt pairs and salts with a common ion have been con-

in former editions on blast furnace equi- libria is to be doubted, although real criticism along this line is unfair. One must draw the line on material to be in- cluded somewhere. The reviewer notes with satisfaction the much more extensive discussion of the Clapeyron-Clansius equa- tion and its application to phase trans- formations. I t is possible to repress mathematics too far in such a work. In fact i t seems a pity that a really satisfac- tory derivation of the phase rule itself has not as yet been included.

MALCOLM M. HARINO

Exercises in General Chemistry. CH-ES M. ALLEN, M.A., Head of the Department of Chemistry, Pratt In- stitute. John Wiley & Sons, Inc., New York City. Second edition. 1927. 63 pp. 20 X 26 cm. 81.75.

This book consists of sixty-two experi- ments covering first-year chemistry. The directions are given clearly with explana- tions when necessary, together with the necessary precautions. The text contains an entire page of laboratory directions, which are omitted from most texts he- cause they appear too obvious, with the result that the student becomes familiar with them only by the end of the term. The attention of the student is called to the things to be observed by questions throughout the procedure, while questions of a general type appear a t the end of each experiment. The manual carefully avoids imparting information which a student can obtain for himself. The experiments in most cases are well selected, but dis- tillation might be carried out more con- veniently with a flask than a retort.

The type is of good size, clear and printed an loose leaves, well secured in a