TO LIBRARIANS OF UNIVERSITIES AND TECHNICAL INSTITUTES. EARLY LITERATURE of MAGNETISM The following rare works, duplicates from the Library of Professor Silvanus P. Thompson, are offered for sale. The Collection is offered en bloc; but, if not disposed of before September, offers for individual books will be entertained. For full descriptive Iist apply to Professor Silvanus P. Thompson, Technical College, Finsbury, Leonard Street, London, E. C. Barlowe, Navigators Supply, 1597; Barlowe, Magneticall Advertisements, 1616; Barlowe, A Breife Discovery, 1618; Bartoli, Del Modo di Misurare, 1546; Brugmans, Verwandtschaften des Magnets, 1781; Cabeus, Philosophia Magnetica, 1629; Galileo, de Systemate Mundi, 1635; Garcia ab Harte, Aromatum, 1574; Geuns, Sur les Aimans, Venlo, 1768; Gilbert, De Magnete, 1600 (first folio edition); Gilbert, De Mundo Nostro, 1651; Gyraldus, De Ke Nautica, 1540; Klaproth, Lettre sur l'Invention de la Boussole, 1834 Kircher, Magnes sive de Arte Magnetica, 1643; Norman, Newe Attractive, 1596; Ridley, Magneticall Bodies and Motions, 1613; Taisnier, De Natura Magnetis, 1562; Theophrastus, History of Stones, 1746. Price of the Collection, £80 nett. A Monthly Magazine of Irish Zoology, Botany, and THE ADJUSTMENT OF OBSERVATIONS Geology. Price 6d. With numerous Illustrations. 8vo. IOS. net. CONTENTS:-Introductory-The Astronomical Divisions of the Year-The Agricultural Divisions of the Year-The Various NewYear Days-Conditions and Traditions at Stonehenge-General Architecture of Stonehenge-Astronomical Observations at By the Method of Least Squares, with Applications By THOMAS WALLACE WRIGHT, M.A.C.E. HYDROGRAPHIC SURVEYING. METHODS, TABLES, AND FORMS OF NOTES. 8vo. 8s. net. CHEMISTRY. By N. Monroe Hopkins, Ph.D., Assistant Professor of Chemistry in The George Washington Stonehenge in 1901-Archæological Observations at Stonehenge, CEMENT AND CONCRETE. 1901-Was there an Earlier Circle?-The May and June Worships MACMILLAN & CO., LTD., LONDON. 125. net. By LOUIS CARLTON SABIN, B. S., C. E., Assistant Engineer, Engineer Department, U.S. Army, Member of the American Society of Civil Engineers. Large Demy 8vo. 215. net. PRACTICAL ELECTRO-CHEMISTRY. Second Edition, Revised and brought up to date. EGYPTIAN GOVERNMENT SCHOOLS. NATURAL In view of the extension of Secondary Education in Egypt, applications are invited for new ASSISTANT-MASTERSHIPS in Secondary Schools under the Ministry of Education. Masters to begin work in October, in Cairo or Alexandria, and to teach in English exclusively. Over 400 boys in each School, mainly Mohammedans. In the case of two of the Masters now required, the subject mainly essential is Science (Experimental Physics and Chemistry); six of the new Masters will be principally engaged in teaching Mathematics; the others will be concerned more particularly with the teaching of English, including History and Geography. Candidates should be not less than 23 nor over 30 years of age, have a robust con. stitution, and have taken a University Degree in Honours. They should have experience as teachers: preference will be given to applicants who hold a Diploma in Teaching. Salary £295 per annum (Eg.24 per mensem), rising to £393 per annum (Eg.32 per mensem). Allowance for passage out to Egypt. Teaching hours, on an average, four daily, Fridays only excepted. Summer vacation not less than two months. Applications, with full statement of qualifications and accompanied by copies only of testimonials, must be sent in before July 17, 1906, marked outside "Assistant-Masterships," and addressed to H. J. BoYD-CARPENTER, Esq., Senior Inspector, Ministry of Education, 19 Woburn Square, London, W.C., to whom candidates may apply for further information. TIVERTON HISTORY. (Business founded 1837.) R. F. DAMON, WEYMOUTH, desires to restrict the number of Branches of Science represented in his Museum, and now offers for Sale his ENTIRE STOCK of MINERALS, RECENT SHELLS, INSECTS, CRUSTACEA, ECHINODERMATA, ETC., retaining in future only his GEOLOGICAL COLLECTIONS MIDDLE AND TECHNICAL SCHOOLS. and Reproductions of FAMOUS FOSSILS, also his Collec Applications are invited for the following vacancies. Duties commence in September next. T. Girls' Secondary School and Technical School: Post of ASSISTANT MISTRESS in SCIENCE and MATHEMATICS. Salary, 100 per tions illustrating ANTHROPOLOGY and all relating to early man. These Collections, which can be treated for singly or together, consist of several thousand specimens. JENA LABORATORY GLASSWARE. Young Man, smart, desires Re-engagement high and 8 inches in diameter. as Laboratory Assistant or Steward; 10 years' experience; excellent references; sound knowledge of Chemistry.-Address ASSISTANT, 16 Brynmaer Road, London, S. W. Whole or part time appointment wanted by experienced analyst (age 24) working for examination.-Address "H. L. G.," c/o NATURE. Wanted, Good Mineral Collection, containing good characteristic, and also finely crystallised specimens, correctly named and localised, of all the principal minerals and their varieties. Also a less important collection suitable for elementary study. — GATTY, Benarth, Conway. TYPE-WRITING UNDERTAKEN BY HIGHLY EDUCATED WOMEN ACCUSTOMED TO SCIEN. Dr. HAMPSON'S AIR-LIQUEFIER is now made to a standard pattern, and numbers are in use in University Laboratories and elsewhere in various countries. The whole apparatus is neat and compact and its parts very easily moved; the Liquefier, without stand, being a cylinder 17 inches It begins to liquefy air in from 6 to 10 minutes after the admission of air at from 150 to 200 atmospheres pressure, making over a litre of liquid per hour. It requires no auxiliary refrigerant and produces a perfectly clear liquid which requires no filtering. The operator has only one gauge to watch and one valve to control. HYDROGEN LIQUEFIER to the designs of Dr. MORRIS W. TRAVERS for use in conjunction with Air-Liquefier. For Prices and Particulars apply to the Sole Makers :BRIN'S OXYGEN COMPANY, LIMITED, ELVERTON STREET, WESTMINSTER, S. W. NORWAY 178 tons. ORWAY.-S.Y. "MIDNIGHT SUN." 12 12/- and 28; August 11 and 25. Apply ALBION S.S. CO., LTD., MACMILLAN & CO.'S NEW BOOKS. THE LIFE & EXPERIENCES OF Sir Henry Roscoe, D.C.L., LL.D., F.R.S. With Photogravure Portraits and other Illustrations. 8vo. 125. net. Written by Himself. THE GARTER MISSION TO JAPAN. By LORD REDESDALE, G.C.V.O., K.C.B., Crown 8vo. 6s. Author of "Tales of Old Japan." Extra TIMES.-"Much has been written, and not a little well written, about Japan of recent years. But nothing has been better written than this tale of New Japan by the distinguished author of 'Tales of Old Japan.' HIGHWAYS AND BYWAYS SERIES.-New Volume. DORSET. By Sir FREDERICK TREVES, Bart., G.C.V.O., C.B., LL.D. Illustrated by JOSEPH PENNELL. Extra Crown 8vo. 65. A SYSTEM OF APPLIED OPTICS. Being a Complete System of Formule of the Second of the Third Order, with Examples of their Practical Application. T. Cooke and Sons, Ltd., of London, York, and Cape Town. 4to. Order, and the Foundation of a Complete System By H. DENNIS TAYLOR, Optical Manager to 30s. net. NEW WORK ON ASTRONOMY BY SIMON NEWCOMB. A COMPENDIUM OF SPHERICAL ASTRONOMY. With its Applications to the Deter mination and Reduction of Positions of the Fixed Stars. By SIMon newcomb. 8vo. 12s. 6d. net. AN INTRODUCTION TO ASTRONOMY. By FOREST RAY MOULTON, Ph.D. CHEMISTRY OF THE PROTEIDS. Illustrated. Crown 8vo. 5s. net. By GUSTAV MANN, M.D. (Edin.), B.Sc. (Oxon.), University Demonstrator of Physio logy, Oxford. Based on Professor Otto Cohnheim's "Chemie der Eiweisskörper." 8vo. 15s. net. NATURE." Its many excellences can be discovered by reading it and using it, and Dr. Mann is to be congratulated in having produced such a valuable addition to scientific literature." PRACTICAL EXERCISES IN CHEMISTRY. By G. C. DONINGTON, M.A., Senior Science Master of Leeds All the subjects included in the new syllabus in Chemistry for the Matriculation Examination of the University of London are dealt with in this book. For the New Syllabus of the Preliminary Examination for the Certificate (1907). LESSONS IN SCIENCE. A Preliminary Course of Physics and Chemistry. By Professor R. A. GREGORY and A. T. SIMMONS, B.Sc. Illustrated. THE BIOLOGY OF THE FROG. Crown 8vo. 6s. 6d. net. A MANUAL OF GEOMETRY. 3s. 6d. By SAMUEL J. HOLMES, Ph.D., Assistant Professor of Zoology in the University of Wisconsin. Illustrated. By W. D. EGGAR, M.A., Assistant Master at Eton College. An experimental treatment of Geometry, in which Theorems are taken along with the practical work. NATURE." We know of no text-book of elementary geometry which can be more confidently recommended to teachers, and none from which students are likely to derive more profit." THE BEGINNER'S SET OF MATHEMATICAL INSTRU MENTS. Bow Compass; Dividers; Two Nickel Set Squares (45° and 60° respectively), 4 inches and 5 inches long, two edges of which show inches and tenths and millimetres; Nickel Protractor; double bevelled 6-inch Rule showing inches and tenths and millimetres; and a Lead Pencil. All enclosed in Metal Pocket-Case. Is. 6d. net. THE DYNAMICS OF LIVING MATTER. By Professor JACQUES LOEB. Comprising Pp. i.-viii. + 365. A detailed and descriptive prospectus of this work will be sent post free on application. WORKS BY GEORGE HURST, F.C.S., M.S.C.I. FOURTH EDITION, Revised and Enlarged. With Illustrations. 12s. 6d. PAINTERS' COLOURS, OILS, AND VARNISHES: A Practical Manual. "A thoroughly practical book. . . . The only English work that satisfactorily treats of the manufacture of oils, colours and pigments." -Chemical Trades Journal. In Crown 8vo. Handsome Cloth. With Illustrations. Price 5s. "For the student who is desirous of acquiring Experimental Knowledge, the present volume will be invaluable."-Chemical Trades Journal. PASTORELLI & RAPKIN, Ltd., 46 HATTON GARDEN, LONDON, E.C. Actual Manufacturers of all kinds of Meteorological and Scientific Instruments. Fortin's Standard Barometers. Earth Thermometers. Rain Gauges. Self-registering Rain Gauges. Rain Gauges. Self-recording Barometers. Thermometers. Anemometers. &c., &c., &c. MAY BE OBTAINED THROUGH Illustrated Price List Established 1750. Contractors to H.M. Government. Telephone: 1981 Holborn. Telegrams: Rapkin, London. N.B.-If any difficulty in obtaining our Instruments from your Dealer, kindly THURSDAY, JULY 12, 1906. PHYSICAL CHEMISTRY APPLIED ΤΟ Cours de Chimie physique suivi d'Applications à la THI HIS volume forms a portion of the first part of a treatise on physical chemistry and its applications to chemistry and biology, evidently intended for readers commencing the specialised study of physical chemistry, but possessing some considerable knowledge of chemistry and biology. The subjects described in the thirteen chapters of this first part are as follows:-General conditions of equilibrium in solutions; electrical conductivity of solutions; ionic theory; conductivity in non-aqueous solutions; osmosis and osmotic pressure; diffusion; cryoscopy; vapour pressure and boiling-point of solutions; absorption and solution; solubility and coefficient of distribution in solution; surface tension and viscosity of solutions; optical properties of solutions; electrical phenomena in solutions, study of galvanic and concentration cells (incomplete). The general scheme of treatment which the author outlines in his preface consists in describing in each case (1) the methods of measurement used in studying the particular phenomenon under consideration, (2) the experimental results obtained, and (3) the hypotheses and general theories which make it possible to connect together the experimental results and also others obtained by different experimental methods. This method of presenting experimental results apart from the theory which may have given birth to the observations, or have formed a connecting link for correlating them with other known facts, may be most philosophical, and occasionally most desirable, in order to impress upon the mind of the student that the observed facts exist apart from any theory, as has been most ably done by the present author, for example, in chapters i., ii., and iii. of his treatise. At the same time it can and does become a cumbrous and space-robbing form of description, and much beauty is lost by not placing the facts at once in the appropriate setting of the theory which lead the mind to the planning of the experimental work which established the facts. most It is no doubt quite possible that a mathematical treatise might be written without the use of any symbols or any conventions of any type, or that a treatise on chemistry might be written consisting of bare, dry experimental facts without any reference to the atomic theory. Such treatises would be most interesting as monuments of human perseverance and industry, and would be literary curiosities of the highest order; but it is questionable if they would be very intelligible, and certainly they would be very lengthy, and most unstimulating to the student or worker, who could not proceed a step further with their aid alone in the way of advance, but would at once have to proceed to formulate a theory if it were desired to carry out an experiment differing in type from any in such a non-theoretical treatise. Without a theory in advance there can be no such thing a intelligent experimentation; after experimentation, the theory must be adapted where necessary to experimental results, or, if necessary, a new theory formulated which will lead to further experimentation. It is therefore a relief to find that after the first three chapters the author somewhat alters his plan, accepts the ionic theory, and speaks boldly of ions. Some of the aspects in which the ionic theory, as at present held, fails to account for experimental facts are pointed out in the book, and those many experimental observations which are accounted for, and correlated, by the theory are justly held up for welldeserved admiration. The author is also to be congratulated upon not having too thoroughly carried out the intention expressed in his preface of making the mathematics of physical chemistry problems easy for the nonmathematical reader. The authors who invent and perpetuate this style of mathematics made easy surely forget that a reader who has not a rudimentary notion of how to apply the calculus probably has not learnt his more elementary mathematics well enough to follow the solution of their long and involved series and equations, and if he ever did has probably forgotten it long ago, and therefore skips the proof and accepts the conclusion much as he would have done had the proof been given in the shorter way. As stated above, anything which can be put or proven in mathematical symbols could also be equally put or proven in ordinary words, provided patience and perseverance could be provided on the part of the author to write it, and of the reader laboriously to wade through it; but when there is a better method, surely it is much better for the non-mathematical reader to accept his mathematics ready made for him, or, if he objects to doing this, take up the study of mathematics a little longer and then turn to its applications. It is accordingly a relief to find that the author does not carry his threat of making mathematics easy too far, and employs the calculus where necessary. Regarding the subjects treated in the first part so far as they are contained in the present volume, it may be said that on the whole the style of treatment is most interesting, and the information usually full and carried well up to the present date. Occasionally it would have been well, as the work is obviously intended specially for biological students interested in physical chemistry, if the biological aspects had been treated at greater length, as, for example, in the section on the theory of indicators on p. 110, and that on the study of the fluids of the organism, p. 114; but it is possible that the author may intend to return to these subjects at a later part of the work. The descriptions of how to carry out experimental work given in the volume are clearly intended to enable the student to carry on experiments, for the |