346 NATURAL SCIENCE. May. 



it is none the less true that Prof. Strasburger's work remains at the 

 head of all guides to the study of laboratory botany. No pains have 

 been spared to render the " Practicum " more useful than ever to the 

 practical worker. It may have lost something in freshness and in 

 general botanical interest, but in completeness and elaboration of 

 detail, it stands unrivalled as a guide to histological method. 



D. H. S. 



A New Edition of Brush's Mineralogy. 



Manual of Determinative Mineralogy. With an Introduction on Blowpipe 

 Analysis. By George J. Brush. Revised and enlarged by Samuel L. Penfield. 

 Fourteenth Edition. 8vo. pp. ix., + 164+63 to 96 in double-page tables+ioi to 

 108 of Index, with 50 figs. London and New York : Chapman and Hall. 1896. 

 Price 15s. 



The appearance of a new revised and enlarged edition of this well- 

 known text-book is an event worth recording. As the result of 

 Professor Penfield's work, the book, although retaining the general 

 plan of previous editions, has been practically re-written, and at the 

 same time almost doubled in size by the addition of new matter and 

 illustrations. The additional matter includes an introductory chapter 

 giving a summary of important chemical principles. These are 

 enunciated very clearly but, we fear, too briefly to be of much 

 service to the student (for whom they are presumably intended) who 

 has had no previous knowledge of chemistry. 



The chapters on apparatus and re-agents have been considerably 

 extended, but follow on the whole the lines of the last edition. It is 

 in the chapter on the reactions of the elements that the greatest 

 departure from previous editions will be noted. From barely 14 pages 

 this chapter has now been extended to 94. The elements, in 

 alphabetical order, are treated under the headings, Occurrence and 

 Detection. The enumeration of the principal minerals in which each 

 element occurs is a new and useful feature. Where blowpipe tests are 

 not decisive, full details are given of tests in the wet way : e.g., in the 

 case of the rare earths, the general methods of separation by means 

 of oxalic acid, sodium thiosulphate and potassium sulphate are 

 described. In this connection, however, we note at the bottom of 

 page 65 a sentence which is so worded as possibly to lead the unwary 

 student to the erroneous conclusion that Thorium may be separated 

 from Zirconium by a double precipitation with sodium thiosulphate. 



The descriptions of tests with known minerals which are given in 

 smaller type under most of the elements are very suggestive and 

 instructive. Throughout the book particular care has been taken to 

 point out to the student the precautions necessary to insure success 

 in any test ; thus he is warned that in the case of fused material a 

 blue colour with cobalt nitrate is not necessarily an indication of the 

 presence of alumina, and that in testing for carbonates concentrated 

 acids must not be used nor ebullition mistaken for effervescence. We 

 are glad to note the subsidiary position assigned by the author to 

 those stumbling-blocks, the cobalt nitrate test for magnesia and the 

 microcosmic bead test for silica. That the book is well up to date 

 may be judged by the fact that at least half a dozen lines are devoted 

 to the consideration of Helium. 



As stated in the preface, the book, as it is now presented, is only 

 the beginning of a revision, for the tables for the determination of 

 minerals have been left as in the last edition by Professor Brush. A 

 complete revision of these tables, however, is to be made as soon as 

 possible, and a chapter added on crystallography and the physical 

 properties of minerals. G. T. P. 



