Dec. 2 2, 1887] 



NA TURE 



175 



that, outside certain fundamental operations and stages 

 in teaching, teachers and schools differ considerably in 

 detail, and it is precisely on this detail, or order of import- 

 ance in some cases, of work that a teacher prides himself 

 — or thinks he has the right plan— as being able to turn 

 out the most satisfactory students or to save their 

 time. 



The author of this book in his preface tells us that a 

 preliminary edition wj.s issued a little more than a year 

 ago for his own students, and that the work had been 

 even before then in use as a typographed book for some 

 time. He likewise makes some remarks about the drill- 

 ing of students in the beginning of their quantitative 

 exercises with which we fully agree. Our experience 

 is that a student requires standing over during the first 

 four or five quantitative exercises. If the author's pro- 

 duction shortens that ever so little, it will be a service to 

 teacher and student alike. As to the interpolation of a 

 preparation, the importance of this has scarcely been re- 

 cognized by teachers. There is no doubt that a judicious 

 selection of preparations, the end product of which is to 

 be analyzed, is one of the best methods of preparing young 

 students for practical analytical work. 



After the exercises in weighing and measuring and 

 determination of specific gravities of solutions, the book 

 proceeds to a series of exercises in analytical methods. 

 In these methods lies at once the strength and weakness 

 of the book. We have a considerable number of methods 

 for the analysis of things — salts, &c. — of technical import- 

 ance, the performance of which would leave a student in 

 a strong position as regards practical knowledge ; but it is 

 very questionable indeed if the average student could work 

 through the majority of these, in the absence of the 

 instructor, from what is given in the shape of directions. 

 The exercises under separation are very well selected. 

 They include a number of ores and alloys, silicates, &c. 

 In the process of separation of lead and antimony by 

 chlorine (p. 137) the author might have improved on the 

 use of manganese by using permanganate, the evolution 

 of chlorine is more regular. 



Then follows combustion analysis for C, H, and N, and 

 gas analysis. The latter forms the largest and best 

 section of the book. It is mostly taken from, and is after 

 the style of, Bunsen's gasometry. Other methods or 

 modifications are also discussed as far as is requisite in a 

 book of this nature. We have, finally, a number of 

 "promiscuous exercises" in applied analysis: sea- water 

 — mostly after the author's report on the composition of 

 ocean water — milk, butter, and other substances. 



On the whole, the book is a careful compilation and 

 arrangement of work for students, bearing unmistakable 

 evidence of the author by the references to his work and 

 methods. We take leave to object to " Knallgas " as not 

 being very generally understood by English students. It 

 is not much shorter than electrolytic gas, and although 

 the employment of it is explained it serves no very useful 

 end. But this and one or two other details are not great 

 objections, and do not detract from the utility of the book, 

 which attempts perhaps too much, but may be fairly com- 

 mended to those students of chemistry intending to 

 become analysts, especially of technical products. 



W. R. H. 



THE STUDY OF LOGIC. 

 A Short Introduction to the Study of Logic. By 

 Laurence Johnstone. (London : Longmans, Green, 

 and Co., 1887.) 



'T'HERE is naturally some interest attaching to a book 

 -L on logic which bears the imprimatur of Cardinal 

 Manning, and of which a responsible member of the 

 Society of Jesus can say nihil obstat. The Jesuits have 

 long been famous teachers, and it is possible that those 

 who find elementary logic an unsatisfactory teaching- 

 subject may glean some useful hints from this little 

 volume. 



From a point of view outside the Roman Church, the 

 perennial difficulty in the study of logic consists in the 

 fact that no firm line can be drawn between the most 

 elementary logical doctrines and the highest possible 

 flights of philosophical reflection. As logic is taught by 

 and for free-thinkers, both student and teacher are in a 

 constant state of climbing ladders only to kick them 

 down. At all stages a higher and a lower logic are at 

 variance, or rather the higher logic consists in nothing 

 else than a criticism of the lower. Distinctions that have 

 been our mainstay become mere obstacles: our later 

 views are mostly not additions to the earlier ones, but 

 subversions of them. Hence there is little beyond the 

 bare history of the subject, and a few of the less important 

 technicalities, that can be taught with any authority. 



In Mr. Johnstone's book we find throughout a wholly 

 different attitude taken. With quiet simplicity, questions 

 over which modern philosophy has spent much heat and 

 labour are boldly prevented from arising. Thus a student 

 may read, on page 10, under the heading " Action of the 

 Intellect," that " the mind is a tabula rasa before it re- 

 ceives any impressions from without. It receives im- 

 pressions, or the matter for ideas, through the senses, 

 upon which the impression is made. By means of the 

 ' sensus intimus' man becomes conscious of these im- 

 pressions, of which the imagination then forms a picture, 

 or phantasm." And then " from the picture on the 

 imagination the intellect draws that element which is 

 akin to itself, that is the immaterial incorporeal element, 

 throws it into its mould — so to say — and the result is the 

 ' species intelligibilis,' formed in the intellect itself, and 

 representative of the exterior thing." What could be 

 more final and satisfactory ? It is not everyone who is 

 free to make so short a piece of work of one of the largest 

 of all philosophical questions. And so the student gets 

 something that he can definitely carry away, and produce 

 on paper when required. 



Another noticeable feature is the revival, throughout 

 the work, of many distinctions which have dropped out 

 of sight in our modern text-books, or are at most referred 

 to vaguely there with a passing smile at the " fruitless 

 subtlety of the schoolmen." These can plainly be made 

 to serve two purposes, — they provide abundance of 

 material for the student to exercise his memory upon, 

 and their effect as a whole must be to keep as separate 

 as possible the process of using the machinery of logic, 

 and that of seriously criticising our own beliefs. It is 

 only from the free-thinker's point of view that any real 

 desire can be felt to make logical criticism practically 

 effective to the utmost. If we are anxious above all to 



