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also having a limiting characteristic in agreement with the extent of the atomic numbers. The deduction therefrom follows that these missing element,s do not exist, or if they do exist are present in exceedingly minute quantities,” p. 2 9 . “The relative distribution of elements in the earth’s crust, according to the findings of Clarke and Washington, is tabulated and shown to support the view that scandium exists in relatively small quantities compared with the quantities of calcium and titanium situated on each side of it in the periodic table, and this fact strengthens the conception of a significant atomic number series, thereby earmarking the periodic places where no elements can fall, or if they do fall into such places the quantities will be exceedingly minute,” p. 35. “The existence of scandium in the sun does not necessarily invalidate any relative quantitative deduction as to the proportionate amount of this element relative to those on each side of it in the atomic-number series; for the sun may be manufacturing or degrading practically all of the existing elements, and any excess of one in particular may not appear in large relative quantities in the final state when this process of manufacture and (or) degradation is finished,” p. 44. Wilder D. Bancroft Problems in General Physics for College Courses. By Morton Masius. Second revised and enlarged edition. d l -+14 cm; p p . x+164. Philadelphia: P. Blakiston’a Son and Co., 19.94. Price: 8d.00. The first edition was reviewed in 1918 (22, 458). The second edition contains nearly four times as many problems. The reviewer is glad to endorse the sentiments on p. 4. “It is manifestly impossible to memorize ready-made formulae for all possible cases. Hence the general plan of memorizing only the most important relations, and making the necessary deductions from them according to the problem under discussion. All students will admit the force of the argument just given, but another question may now arise. If, in general, it is a safer plan to rely not on a large number of memorized formulae, but on the power of being able to deduce the special formula required for a particular problem, is any memory work required at all? Would it not be better to leave everything to reasoning power and not memorize any formulae? The answer to these questions is: No. The reason for this is very simple. In the list of the equations that are to be memorized we have included two kinds: ( I ) those that express the fundamental laws, (2) those that occur very often. The reason for memorizing those of the second class is obvious. As regards those of the first class we must recall that no amount of logical reasoning, however original and profound, can produce a definition or a fact. A knowledge of a few definitions and facts is necessary, and all relations representing them have to be memorized.”
Wilder D. Bancroft ERRATA I n the paper by Messrs. Bhatnagar and Shrivastava the heading of column 6 in Tables 11-VII, pp. 733-738 should be changed from “Quantity of sucrose [glucose, galact.ose] adsorbed per IOOCC of the mixed solution examined” to “Quantity of sucrose [glucose,galactose] adsorbed per IOO cc of the sugar solution”; and the headings of Column 7 in the same tables should be changed from “Quantity adsorbed per IOO cc of the sol” to “Quantity adsorbed by the mixture containing I O O cc of the sugar solution and the sol in the corresponding ratio indicated in Column 2. I n the paper by Mr. Perry, p. 1c8, t>heequation of state for helium should read: In the article as published, the T was omitted. On pp. 893 and 896 the tit,les and authors have been transposed. The proper heading for the book review on p. 893 is Lehrbuch der Metallographie. By Gustav Tammann. Thr proper heading for the book review on p. 896 is Metallographie in Elementarer Darstellun . BTJRudolf Ruer.
