November 28, 1884. 



SCIENCE. 



501 



Jagnaux's little book treats chiefly of the 

 analysis of minerals, metals, and alloys. Al- 

 though it is not intended for beginners, accord- 

 ing to the author's preface, the details of the 

 various processes are often described with great 

 care ; and, moreover, a considerable amount of 

 descriptive chemistry, mineralog} 7 , and metal- 

 lurgy is introduced, which any practical«chemist 

 in need of such information would certainly 

 prefer to look for elsewhere in a more complete 

 form. While the methods described are in the 

 main those usually followed in certain cases,, 

 one cannot help wondering at the author's 

 choice of method, or at his strange omissions. 

 Thus he describes for the commercial assay of 

 manganese only the method of Levol. Under 

 the head of k Potash and soda ' he mentions no 

 indicator but litmus, directs that this should 

 be used with carbonates and bicarbonates, and 

 says nothing of the convenience of a normal 

 alkaline solution. For the volumetric deter- 

 mination of iron he directs the use of a solution 

 of potassic permanganate, obtained by fusing 

 manganic dioxide with potassic hydrate and 

 potassic chlorate, dissolving in water, and 

 adding nitric acid until the liquid has a purple 

 color. The author calls attention to the novelty 

 of certain methods, but he gives nowhere an}' 

 discussion of the accuracy attainable by these 

 or the older methods ; so that the reader is un- 

 able to judge of their merit without actual trial. 



A very convenient feature of the book is the 

 frequent introduction of tables showing the 

 composition of the more common substances, 

 both natural and artificial. 



In his ' Elements of chemistry ' Prof. F. 

 W. Clarke presents briefly but clearly the 

 more important chemical theories, together 

 with the usual amount of descriptive chemis- 

 try. The student who wishes more extended 

 information will find useful references to larger 

 works «or more special treatises. The hundred 

 or more experiments which are described seem 

 to be well chosen, and, as a rule, require but 

 simple apparatus and inexpensive material. 



A brief sketch of the carbon compounds is 

 introduced, but the author fails to improve the 

 opportunity thus offered to explain the isom- 

 erism peculiar to them. Although he illus- 

 trates (p. 307) the structure of certain meta- 

 meric compounds, he passes over in silence the 

 existence of isomeric propyl, butyl, and amyl 

 alcohols. The fundamental facts of isomerism 

 would seem more important to the beginner 

 than the structure formulae of naphthalene, 

 anthracene, pyridine, or chinoline, or the com- 

 position of populin, fraxin, phloridzin, aesculin, 

 all of which he gives. 



In the excellent advice to teachers with 

 which Dr. Greene prefaces his 'Lessons in 

 chemistry,' he says that t; the object of a 

 limited course in chemistry is not to make 

 chemists of the pupils, but to teach them what 

 chemistry is, what it has accomplished, and 

 what it ma}' accomplish." 



This object he has kept steadily in view in 

 writing the book. While many of the more 

 common elements are treated quite fully, he 

 has very properly omitted entirely all descrip- 

 tion of the rarer elements with which many 

 of the elementary text-books are encumbered. 



The space devoted to the compounds of car- 

 bon is unusually large. Although the treat- 

 ment of the subject is necessarily brief, the 

 student cannot fail to get some notion of the 

 broad field upon which so large a number of 

 chemists are now at work. 



While we can hardly discuss in detail the 

 facts given, and the method of presenting them, 

 we may say that the old formula of Kekule for 

 benzol seems quite as well justified by facts as 

 the prism formula of Ladenburg, which he 

 gives, and that by its means the facts of aro- 

 matic isomerism are more readily rendered 

 intelligible. We would also note that one or 

 two statements with regard to the higher fat 

 acids are misleading or erroneous. 



The plates introduced by Professor Clarke 

 and Dr. Greene, to illustrate spectrum analy- 

 sis, are such distressing caricatures of nature 

 that they might better have been suppressed. 



Dr. Kolbe tells us in the preface to his short 

 text-book that it has been written " to recall to 

 the memory of students who have attended a 

 course of lectures on experimental chemistry, 

 what they have seen and heard," and that in 

 writing it he has adhered to the general prin- 

 ciple which should lead the lecturer in chemistry, 

 and that is, " to give to his hearers an idea of 

 chemical processes and the most important 

 chemical theories without burdening their mem- 

 ories with a large number of mere facts." Ad- 

 mirable as this principle may be. it does not 

 seem to have led the author, in this case, to 

 give us any thing particularly novel, at least as 

 far as the descriptive portions of the book are 

 concerned. Its style, it is true, is fresh and 

 entertaining ; and yet we can hardly agree with 

 the editor in thinking that it will supply any 

 definite want among teachers or students. 

 Aside from the purely descriptive portion, 

 which certainly is admirable, the book seems 

 to possess a decided disadvantage, in that the 

 necessary theoretical introduction is unsatis- 

 factory. It is true that the editor has done 

 his best to remedy its defects by introducing 



