SEPTEMBER. 1950
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the dozens of students encountered at all levels who, if they express an opinion a t all, think that the rate of an oxidation by dichromateis proportional to the 14th power of the H+concentration. This is all the more embarrassing because we teach our students that the concentrations that exist under a particular set of reversible equilihrium conditions are independent of the rates involved. There are only two ways of treating the equilibrium constant on a general, valid basis: the first is to say that the exprimatal msults ~ e p i m that the coefficients correspond to the balanced equation, and the second is to admit that the exponents are the coeficients of the partial mokl f ~ e eene~& of the reacting comvonents. This situation is a dilemma. The att.emnt to solve it
These have been replaced by sections on the general theory of diffusional operations, furnaces and kilns, and subsections on dialysis, size enlargement, multi-component distillation, aseotropic and extrmtive distillation, and molecular distillrttian. The new section on the general theory of diffusional operations by A. P. Colhurn and R. L. Pigford is most welcome and serves as an excellent introduction to the following sections on distillation and sublimation, gas absorption, solvent extraction and dialysis, humidification, drying, and adsorption. The libraries serving engineers and the individual chemical engineera have long realized how essential the "Chemical Engineers' Handbook" is in their work. The chemical library should realize that this handbook contains a wealth of cherhicd data arranged for practical use, that it explains the terminology and background of the chemical engineering article being read by the chemist, and that it explains the translation of chemical manipulations, as distillation, filtration, drying, from the lahoratory to plant operations. The chemist must know how and why the chemical eneineer will modifv his laborstorv stem in ex-
calculated that a conce;ltration of 16 M H + would de necessary to prevent the precipitation of CdSl Most students should know that concentrated HC1 is only 12 M. But these calculations are opposed in spirit to the experimental aspect of the subject; equally important, thby fail to point out the differences in behavior of HCI and H.S04. This is a particular example of a general tendency throughout the book. We should not expect a epturated solution of Pbo(P04)~ to contain unhydrolyzed P 0 4 i P ions as the only species of phosphate present, but this assumption is implicit in one of the standard problems on page 71. The vulnerable nature of some solubilitv constants can be shown bv 0 which one can use such constants with any certainty is quite narrow. The maturing chemist learns theae limits, hut current texts in qualitative analysis could do much to catalyze his growth in knowledge. They would probably come nearer to the truth if they were a hit hazier %bout solubility products of the metallic sulfides, and treated the two groups as resembling two galaxies whose members are placed with approximate coordinates. Then it could be said that, with a few exceptions, the members of each galaxy can be kept out of each other's way. The instructor who wants a reliable laboratory manual can choose this book with confidence. The very few typographical errors of the earlier edition have been virtually eliminated. ROBERT EPPLE Bnowlr UNIVERBITY PROVIDENCE, R ~ D ISLAND E
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CHEMICAL ENGINWS' HANDBOOK
John H. Perry, Chemical Engineer, E. I. du Pont de Nernours and Co., Editor. Third edition. McGraw-Hill Book Co., New Yo*, 1950. xv 1942 pp. 19 X 26 cm. Textbook edition, $12.50.
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ONLYthe title appears familiar an the new edition of the "Chemical Engineers' Handbook." The editor and publishers realized that the book was a reference volume that was kept on the desk or book shelf within easy reach, that the charts and curves bed to be large enough to he read accurately, and that the important advances since the second edition in 1941 had to be included. This has been accomplished in the third edition by expanding the page size from 12 X 18 cm. to 19 X 26 om. and arranging the descriptive material in two columns. Tables and charts can now cover the entire page, and hence numerical values can be read from the graphs with sufficient accuracy for engineering calcnlations. Editor Perry has heen assisted by over 140 speciallists who have prepared the various sections and suhsections relating to their specialty. The sections themselves have been critically rearranged with the elimination of several, as qualitative snalysw, organic chemistry, and report writing.
KENNETIi A. KOBE
PATENT PRACTICE AND MANAGEMENT
Robert Colvert, Patent Attorney, New York. Soarsdale Press, Box 536, Scaradale, New York. xi 371 pp. 7 photographs. 16 X 24.5 om. $5.
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TAISbeautifully printed hook makes an immediate appeal and it soon becomes evident that it is as interesting as it is elegant. Without making insidious comparisons, we believe that it is perhaps the best general account that has been written of American patent prectioe. The subject is opened by a discussion of what can be patented. What can he classed as a "new and useful invention?" The great inventions of yesterday were often embodiments of clearout, unit ideas. Important industrial inventions today mare likely to he accretions of many minor ideas, each of limited patentable novelty. At certain stages the firm's patent lawyer will often question whether the inventor has in fact invented anything. Your reviewer's reply to these incredulities would run thus: "Have you ever heard of a device like this that operated efficiently?" "No." Well, this one does. Will you please patent the difference." Recognizing and describing the difference between the workable and the unworkable is the essence of the patentee's task. The author's next concern is the assignment of correct authorship to an invention, without which the patent is liable to he held invalid. There is a. tendency today to conventionalize inventorship. According to one convention, it is the owner or senior employee who gives instructions to the fabricator, who is considered to be the inventor. According to another it is the man who actually makes the invention, in a. physical sense; joint inventorship is not in favor. Our own feeling is that when invention is by accretion most novel ideas are group ideas which emerge from a school of thought, and it is as inaccurate as it is unfair to select a single individual to adorn the printed patent, even though a single member of the group appeared to "exhibit the divine spark of genius." Patents taken out in established industry involve two obligations, assignment to the employer and reward to the employee. Mr. Cdvert shows us that there is very little uniformity of practice in either matter, though a standard code of ethics and treatment is sorely needed. The amateur will find two chapters partiiculmly informative: how to draft a patent with its preamble, subject matter, and claims, and how to lodge the patent and use the facilities of the
