The _Manual of Determinative Mineralogy_ of Professors _George J. Brush_ and _Samuel L. Penfield_[48] is intended primarily to be used in the identification of minerals, and that purpose has been kept prominently in view. The present edition is a complete revision of Professor Brush's original work, the value of which and the estimation in which it is held by its constituency are attested by the fact that fourteen editions of it have been issued since it first appeared in 1874. A revision of the parts devoted to blowpipe analysis and the chemical reactions of the elements was published in 1896. To the present edition a chapter is added on the physical properties of minerals, devoted chiefly to crystallography, in which the endeavor has been made to present the subject as simply as possible. Importance has been attached to the description of those forms which are of most frequent occurrence, and the examples chosen to illustrate the different systems represent, as a rule, the simple forms that prevail in specimens of common minerals, while rare and complex forms are treated very briefly. The introduction of a large number of species since 1874 has made a complete rearrangement necessary in the analytical tables; and they have been so developed that tests for characteristic chemical constituents furnish the chief means of identification. Stress is laid upon the importance of determining the chemical constituents as a factor in securing accuracy in identification. Demonstrator _G. S. Newth_ opens his _Manual of Chemical Analysis_[49] with a protest against the thought of "doing" analysis without learning more than the minimum amount of chemistry, and against teaching and practicing it in such a manner as to degrade it to the level "of a purely mechanical and often unintelligible series of rule-of-thumb operations." He says he has done his best to make it "as little of a cram book as possible," and has endeavored "to teach analytical chemistry as well as analysis"--that is, the theoretical as well as the practical side of the subject. He begins with emphasizing the importance of the student making himself _practically_ familiar with certain simple operations he will have to perform constantly, and gives clear, concise definitions of such terms as filtration, solution, evaporation, fusion, precipitation, ignition, etc., which relate to those operations. He condemns slovenly formulas and mechanical notes, but commends real notes of the student's own observations. In his treatment he excludes merely descriptive details that have no bearing on analysis; and in quantitative analysis, prefers describing fully a few typical methods and processes to covering much ground slightly.