!68 



NA TURK 



[July 20, 1905 



industrial discoveries along these lines have been very 

 far-reaching-. The success attending the investigation 

 of various chemical reactions occurring at high 

 temperatures has caused a marked revival in the 

 interest taken in inorganic chemical research. This 

 has been especially noticeable on the Continent, 

 where, to a much greater extent than with us, the 

 brilliant and rapid development of organic chemistry 

 had led to a marked neglect of this older branch of 

 the science. 



The technical results are hardly less important. 

 Several new and flourishing industries have been 

 firmly established, some of them supplying hitherto 

 unknown materials, which are proving themselves of 

 great value in the arts. A still wider field of useful- 

 ness for the electric methods of heating seems now to 

 be opening up. So far as the electrolytic and high 

 temperature applications are concerned, there has 

 been no direct competition with any existing technical 

 processes. But now that the engineer and chemist 

 have become familiar with the use of the electric 

 furnace, there is a great tendency to extend its 

 employment to work which requires temperatures 

 already attainable by fuel heating if properly applied. 



The possibility of generating the heat just where it 

 is required, the ease of regulation of temperature, and 

 the accompanying economy of heat losses, are the 

 chief factors which tell in favour of electric heating 

 under these conditions. The production of carbon 

 bisulphide and the rapid development of the electrical 

 manufacture of steel form excellent examples of what 

 is being achieved technically in this direction ; whilst 

 even in the laboratory electrically heated tube and 

 muffle furnaces are being largely employed in place of 

 those heated by gas. 



It is with the interesting details of such subjects 

 as these that M. Minet is concerned. In view of the 

 fact that this is but the first part of his complete 

 work, it is impossible to do more than point out these 

 main divisions of the subject. The author has drawn 

 largely on the patent literature, and has copiously 

 illustrated his descriptions with excellent diagrams 

 and with the portraits of many of the leading investi- 

 gators in this field of work. R. S. Hutton. 



0\JR BOOK SHELF. 



Elementarv Microscopy. By F. Shillington Scales, 

 F.R.M.S. Pp. xii + 179. (London : Baillifere, 

 Tindall and Cox, 1905.) Price 3.S. net. 

 No instrument of research has such wide application 

 in various branches of science and commerce as the 

 microscope. It is, perhaps, scarcely too much to say 

 that the principles underlying its construction and use 

 are often disregarded by those who employ it, and 

 sometimes totallv ignored. Any treatise, therefore, 

 on this subject, however unpretentious, is to be cordi- 

 allv welcomed, and the book now under notice is one 

 that should meet a pressing need. It is written for 

 beginners or for those who have used a microscope 

 without troubling to understand it, and who conse- 

 quently have never by any chance used it at its best. 



The book commences with a description of various 

 simple magnifiers and a descriptive diagram showing 

 the essential parts of a microscope. These parts and 



NO. 1864, VOL. 72] 



the various accessories are in turn described more 

 fully, as well as such appliances as are usually only 

 found in the best instruments. 



The most important points, such as substage con- 

 densers and fine adjustment construction, are treated 

 somewhat full}'. .-\s to the choice of a microscope, 

 reference is made to the fact that in medical schools 

 and elementary science laboratories, where the cheaper 

 form of instrument is usually provided, still no in- 

 struction is given as to its use, and that it is too 

 often looked on as a mere magnifying glass. This is 

 unquestionably true, and it is much to be deprecated 

 that, in cases where the microscope performs such 

 an important part in the work of instruction, no 

 attention whatever is bestowed on its principles and 

 use. The most interesting paragraphs in the book 

 are, perhaps, those in which a comparison is made 

 between the English and Continental stand. That 

 the form of instrument now known as the English 

 model is generally much superior in design and con- 

 struction to the Continental stands is admitted and 

 insisted on bv the majority of those whose opinion 

 is of value. .\t no period for many years past has 

 the English microscope stand held such a high place, 

 and it is greatly to be hoped that those who are in 

 a position which gives them opportunities of recom- 

 mending one form or another will recognise this. It 

 is much to be regretted that, so far as objectives are 

 concerned, the same cannot be said. Some English 

 makers do undoubtedly produce lenses of good quality, 

 but the average is not so high, and the finest objec- 

 tives produced by Messrs. Zeiss are still unexcelled 

 bv those of any other makers. In the production 

 of substage optical appliances, this country holds, 

 as it has always done, a very high position, and it 

 is dilificult to understand whv the same cannot be 

 said of objectives. All the usual microscope acces- 

 sories, as well as their method of use, are described 

 as fully as the circumstances permit. 



Chapters vi. and vii. are devoted to the practical 

 optics of the microscope and its manipulation. This 

 is the most important section of the book, and should 

 be carefully studied. Perhaps more space might have 

 been devoted to this, although it is quite easy to 

 understand the difficulties that might arise in at- 

 tempting anything like an exhaustive treatise on 

 microscopic optics, debatable as the subject still is. 



Altogether, the book is to be commended as a 

 genuine attempt to treat the subject in a sim^' 

 straightforward manner, so that the reader for whom 

 it is primarily intended may grasp its meaning with- 

 out difficulty. J. E. B. 



The Practical Photographer's Annual, 1905. Edited 



by Rev. F. C. Lambert. Pp. xxxvi + i6d. 



(London ; Hodder and Stoughton, 1905.) Price 



IS. 6d. net. 

 These pages, as we are told in the preface, are 

 intended to serve no other purpose than to aid the 

 memory of the busy photographer, and if possible to 

 anticipate his daily needs. 



An examination of the book shows that the editor 

 has very successfully accomplished his task, and at 

 the same time has not made the volume of such 

 a bulky nature as to render its size inconvenient. It 

 is true that more references might have been inserted, 

 but such an addition would perhaps be questionable. 



The four sections into which the book is divided 

 include a dictionary of practical hints, dodges, &c. ; 

 a collection of tables, weights, measures, everyday 

 formulae, &c. ; a directory of the photographic societies 

 of Great Britain and Ireland; and finally, a set of 

 indices to the first twelve numbers of the present 

 (library) series of the Practical Photographer. Each 



