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FEBRUARY 13, 1883.] SCIENCE. the student with the means of following up the literaturo of any subject as thoroughly as he may be inclined. The figures are numerous, new, and adinirably fitted to illustrate the points for which they are intendod. Altogether, the book is well suited for the wants of beginners, to whom the size and abstruseness of the larger works on petrography are often discouraging; and it will doubtless fiod many readers in this country as well as in Europe. It would abundantly repay translating into English. SIMON'S Manual of CHEMISTRY. THIS book, as the preface informs ve, is in- tended as a guide to lectures and laboratory work for beginners in chemistry, being espe- cially adopted for the use of pharmaceutical and medical students. It is hard to see, how- ever, in what respects pharmaceutical or medi- cal students need special inethods of treatment in their commencement of the study of chem- istry before they enter upon a story of those particular branches of the science especially necessary to them in their profession. A peculiar feature of the book is the prea- ence of seven colored plates, showing the va- riously shaded colors of the more common chemicals. and their color-reactions; such as the red of mercuric iodide, the yellow of arse- nions sulphide, the shades of color produced by the action of reducing-agents on a solution of potassium dichromnte, etc.,- -a feature which can possess little value to a isboratory student, who must necessarily become familiar with these colored substances and their reactions by personal experience. The book, however, bears the appearance of being intended for students who are to have but little lahoratory work: and, indeed, with the exception of the portion treating of metnis and their combina tions, it cannot be considered as a really good text-book for isboratory use. Thero is noticeable, moreover, throughout the book, an apparent lack of connection be- tween fact and theory. The facts are given, but the theory is lacking. When supplemented by lectures, this defect might not be so notice- able. It is, however, a point to which the student's attention needs to be constantly called. Chemistry is more then a collection of facts: it is a living science. Facts serve as a basis upon which to build theories; and the mutonl connection of fact and theory needs to be constantly indicated, as well as the meth- Manuel of chemistry. By W Surox. Philadelphia, Leo's & Ch., 1954. Linstr. r. 139 ods of reasoning by which the theoretical con- clusions are reached. The book, however, posscases some adinira- ble features. As a whole. It is well written, is systematic, and contains much that is valuable. Its main defect as an elementary text-book consists in tho attempt to cover too grent a variety of subjects at the expense of thorough- ness. Critical examination, moreover, reveals here and there an occasional incorrect or mis- leading statement. Thus, on p. 358 we are told that "ptyalin, the active principle of saliva, is a ferment which has the power of con- verting starch into glucose," whereas it bas been known for the last five years that the main product of the amytolytic action of saliva is of nitrogen, given on p. 241, can hardly bo maltose. The method for the determination considered as the method generally used for this purpose, as is claimed by the author; neither can the method, given on the same page, for the determination of carbon and hy- drogen by passing dry oxygen gas over the subetance heated in a glass tube," be taken as B satisfactory statement of the method gener- ally used for making a combustion' in oxy- gen gas. Again: we are told on p. 859 that pepein, in the presence of free hydrochloric acid, does not prevent the continued action of saliva on starch, whereas it has been plainly demonstrated within the last three years that the ferment of saliva is completely destroyed by gastric juice, and even by dilute hydro- chloric acid alone. NEW TEXT-BOOKS OF PHYSICS. NH. GAGE states his aim to be. “to collate in this volume something of value to every teacher of physical science." The book is divided into five parta: laboratory exercises, manual of manipulation, general review of physics, test-questions, and key to solution of problems. The experimente given in the first part are mostly well enough, and some of them even of considerable ingenuity. They are, however, numbered in a minuts fashion, which is likely to mislead one who reeds in the announcement that there are two hundred and thirty-eight experiments. In the forty- five peges devoted to the manual of manipu- lation, very few directions for manipuletion • Physical Secknice, or. Teacher's manual af physical monip- ulation. c. By ALFRED F, GAGE, A.M. Boston, Author, 1864. 200 p. 5. Problèmes de physique de mécanique, de cosmographie de chimie. Par Kous Jacquin Parle, Geuthier-Villars, 1894. 6271 p 6'.