February 13, 1885.] 



SCIENCE 



139 



the student with the means of following up the 

 literature of an}' subject as thoroughly as he may 

 be inclined. The figures are numerous, new, 

 and admirably fitted to illustrate the points for 

 which they are intended. 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 find 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 us, is in- 

 tended as a guide to lectures and laboratory 

 work for beginners in chemistry, being espe- 

 cially adapted 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 methods of treatment 

 in their commencement of the study of chem- 

 istry before they enter upon a study of those 

 particular branches of the science especially 

 necessaiy to them in their profession. 



A peculiar feature of the book is the pres- 

 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- 

 nious sulphide, the shades of color produced 

 by the action of reducing-agents on a solution 

 of potassium dichromate, etc., — a feature which 

 can possess little value to a laboratory student, 

 who must necessarily become familiar with 

 these colored substances and their reactions 

 hy personal experience. The book, however, 

 bears the appearance of being intended for 

 students who are to have but little laboratory 

 work ; and, indeed, with the exception of the 

 portion treating of metals and their combina- 

 tions, it cannot be considered as a really good 

 text-book for laboratory use. 



There 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 than a collection 

 of facts : it is a living science. Facts serve 

 as a basis upon which to build theories ; and 

 the mutual connection of fact and theory needs 

 to be constantly indicated, as well as the meth- 



Manual of chemUtry. By \V r . Simon. Philadelphia, Lea's 

 son <fc Co., 1884. illustr. 8°. 



ocls of reasoning by which the theoretical con- 

 clusions are reached. 



The book, however, possesses some admira- 

 ble features. As a whole, it is well written, is 

 s}'stematic, and contains much that is valuable. 

 Its main defect as an elementary text-book 

 consists in the attempt to cover too great a 

 variet} r 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 has 

 been known for the last five 3-ears that the main 

 product of the amylolytic action of saliva is 

 maltose. The method for the determination 

 of nitrogen, given on p. 241, can hardly be 

 considered as the method generally used for 

 this purpose, as is claimed b} T the author ; 

 neither can the method, given on the same 

 page, for the determination of carbon and Iry- 

 drogen " by passing dry ox}~gen gas over the 

 substance heated in a glass tube," be taken as 

 a satisfactory statement of the method gener- 

 ally used for making a ' combustion ' in oxy- 

 gen gas. Again : we are told on p. 359 that 

 pepsin, in the presence of free Irydrochloric 

 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 destined 

 by gastric juice, and even by dilute hydro- 

 chloric acid alone. 



NEW TEXT-BOOKS OF PHYSICS. 



Mr. 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 parts : laboratory exercises, 

 manual of manipulation, general review of 

 physics, test-questions, and key to solution 

 of problems. The experiments given in the 

 first part are mostly well enough, and some 

 of them even of considerable ingenuit}\ They 

 are, however, numbered in a minute fashion, 

 which is likely to mislead one who reads in 

 the announcement that there are two hundred 

 and thirt3 T -eight experiments. In the forty- 

 five pages devoted to the k manual of manipu- 

 lation,' ver} 7 few directions for manipulation 



Physical technics, or, Teacher's manual of physical manip- 

 ulation, etc. By Alfred P. Gage, A.M. Boston, Author, 18S4. 

 200 p. 8°. 



Problemes de physique de mecanique, de cosmographie, de 

 rhimie. Par Edmb Jacquier. Paris, Gauthier- Villars, 1SS4. 

 6 + 271 p. 8°. 



