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excellent work has grown out of the exigencies of chemical teaching. In its earliest form it appeared in 1864, and passed through several editions. It was intended to be used, with Fresenius's "Manual of Qualitative Analysis," as a guide to the experimental study of substances to be made in connection with analysis, but beyond its immediate requirements. It is now revised and enlarged so as of itself to answer the needs of the student, and relieve him from the necessity of obtaining more than one text-book for inorganic qualitative work. Its aim is stated to be, "to aid the student in gaining an accurate acquaintance with the facts whereby analyses are made; and a clear understanding of the coördination of these facts—the principles of analysis—has been the chief object of this work. It is the result of experience in the constant endeavor to prevent habits of automatic operation and of superficial observation in analysis." Various improvements in the work are pointed out in the preface to the new edition, which have been arrived at by the experience of the last ten years, and which bring the volume up to the requirements of the times.

work is designed not for popular reading, but for practical students of chemistry, and will answer the purpose of a kind of condensed library of technical information, in which the ordinary text-books are deficient. Compiled by a working student, from the needs of his own experience, it cannot fail to be useful to others in similar circumstances, who will find the labor here done to their hand which they would otherwise have to do for themselves. The author has prepared the work on the principle that every scientific man "should compile his own pocket-book, as he proceeds in study and practice, to suit his particular business." Having accumulated from time to time a large number of valuable notes, tables, and chemical data, which became too voluminous to be carried in the pocket, he then decided to extend, systematize, and publish them. Dr. Charles F. Chandler, Professor of Chemistry in the Columbia College School of Mines, introduces the work by a brief preface, in which he says:

Mr. Van Nostrand has got the work out in excellent style, and we have only to make a small complaint of the inartistic monotony of the page-headings, which simply reproduce the title of the book, without giving any guidance to its successive subjects and the variety of its contents.

manual first appeared twenty-five years ago, and he now issues the third edition, rewritten and greatly enlarged. In regard to his object in preparing the volume, the author says: "It is proposed in this treatise to give such a resume of microscopy as shall enable the student in any department to pursue original investigations with a general knowledge of what has been accomplished by others. To this end a comprehensive view of the necessary instruments and details of the art, or what the Germans call technology, is first given, and then a brief account of the application of the microscope to various branches of science, especially considering the needs of physicians and students of medicine." The sciences here referred to are