technical features of patent law. Thus, there is a relatively Long chapter on what constitutes invention. This is followed by chapters on t h e prepastion and prosecution of applications, the essentials of a valid patent, and patent rights and their enforcement. There is a discussion of proper methods of keeping invention records. Finally, there is a glossary of 17 pages of definitions of terms frequently used in patent practice. The hook is dearly and interestingly written. Numerous decisions and authorities are quoted a t appropriate places. The ,author neither attempts to improve upon the language of the Supreme Court, for example, nor quotes decisions in a disconnected manner. Thus, he avoids two errors that are common in works of this kind and gives an orderly and logical presentation containing reviews of numerous cases to illustrate important points. The chapter dealing particularly with the enforcement of patent rights is somewhat more brief than its importance would justify. Thus, there is no mention of the important matter of limiting disclaimers, by which the scope of a claim may be limited without its being disclaimed as a whole. It is a pleasure to record that one who is so eminently qualified has presented a work that is worthy of him. RosEnr CALVERT 292 MADISON
AVBNUB
NBW Yon=, N. Y.
Construction of a Diagnostic Test in the Mechanics and Related Fundamentals of High-School Chemistry. JOSEPHE. MALIN. Williams BTOS.,Philadelphia, Penna., 1932. 261 pp. 15 X 23 cm. 81.50. This study of the "mechanics and related fundamentals of high-school chemistry" is confined to the "principle of valence; principle of writing formulas; principle of writing equations; principle of solving numerical chemistry problems; laws and theories directly related to the
aforementioned principles; and the properties of gases." The author selected a body of test material to be used in diagnosing the difficulties met by high-school students in their study of the features of these "principles" that are treated in the texts used in high-school classes. I n the selection of the items of the test, the author was guided by "the criterion of extrinsic use. criterion of errors, a composite of textbooks, a composite of requirements in courses of study, a composite of teachen' examinations, and the judgment of experts." T h e results of analysis of texts, laboratory manuals, and examinations, are given in detail. The results of the analysis were then submitted to chemistry teachers t o determine the extent to which the items selected by analysis were actually used by classroom teachers. Two tests were constructed, each of 50 items, and used with a large number of students. The tests were used twice during the year, but not with the same s t u d e n t s m c e near the middle of the school year and once a t the end of the school year. The results from the examinations were analyzed and tabulated to show in detail the types of errors t h a t were made. The original tests were revised on the basis of the results obtained from the analysis and printed as Forms X and Y. The tabulations show in considerable detail the types of errors made by highschool students. These errors suggest the kinds of difficulties encountered in study, and may therefore serve t o guide teachers in applying remedial measures. This reviewer feels some concern about the emphasis on "mechanics" in this and some other work that has been reported. Teachers who use this work should not conclude that equations and formulas should be learned in chemistry in the same way t h a t spelling and multiplication are learned. Students should use chemical equations t o describe chemical changes that they have studied and not as a sequence of symbols t o be memorized.
