SECOND-HAND MICROSCOPES, &c. Second-hand Microscopes and Apparatus by Zeiss, Leitz, Ross, R. & J. Beck, Swift & Son and Watson & Sons; the largest selection in London. Price List post free on application. Also Second-hand Telescopes, Prism and other Field Glasses and Mathematical Instruments by all the leading makers. Price List post free on application. MILLIKIN & LAWLEY, 165 Strand, London, W.C. OLD PLATINUM, GOLD Scrap, &c., valued or purchased. SPINK & SON, Ltd., 17 & 18 PICCADILLY, W., and at 6 KING STREET, ST. JAMES', LONDON, S.W. Gems for experimental work at moderate prices. SUCCESSFUL INVENTORS HAVE THEIR IDEAS WORKED OUT AND MODELS MADE AT Wm. K-L. DICKSON'S Transparent Fused Quartz This is a photograph of an "Assay Set" made from quartz rod and tube, a copy of a platinum model, and holds thirteen prill cups. The price of this set is 38/6. We supply other sizes at proportionate prices. Such a piece of apparatus of ordinary glass would be useless, but made of quartz glass is an excellent example of the uses of what has been termed "poor man's platinum." Illustrated Price List and Sample of Tube free THE SILICA SYNDICATE, Ltd., 82 HATTON GARDEN, LONDON. DARTON'S IMPROVED SELF-RECORDING BAROGRAPH for accurately recording variations in temperature. New Illustrated List of Standard Meteorological Instruments, F. DARTON & Co., 142 St. JOHN STREET, LONDON, E.C. LIQUID AIR AND LIQUID HYDROGEN. 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 high and 8 inches in diameter. 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 of the above and commercial apparatus of the same description manufactured under the Linde and Hampson patents apply to THE BRITISH OXYGEN CO., Ltd., (Formerly Brin's Oxygen Co., Ltd.) ELVERTON STREET, WESTMINSTER, S.W. MERCK'S DFREAGENTS & CHEMICALS For ANALYTICAL, MICROSCOPIC, BACTERIOLOGICAL and PHOTOGRAPHIC PURPOSES, are the STANDARDS OF PURITY, RELIABILITY AND To be had through the regular Trade Channels, or E. MERCK, 16 Jewry St., LONDON, E.C. Head Office and Works: DARMSTADT. W. WILSON. STUDENT'S SPECTROMETER. Telescope and prism table reading to 1 min.; clamp and fine adjustment to both. Rack-motion to telescope; prism table adjustable vertical and horizontally. Adjustable slit to collimator. Protected circle. In case. £6 0 0 A very large number of these instruments have been sold, and have given exceptional satisfaction. 1 BELMONT STREET, LONDON, N.W. Telephone: 5712 Westminster. INDISPENSABLE TO LECTURERS AND STUDENTS. THE ONLY COMPLETE MODEL WIRELESS TELEGRAPH APPARATUS. It can be worked from room to room, or house to house. TELEGRAPH & TELEPHONE INSTRUMENTS, LTD., 25 VICTORIA STREET, LONDON, S.W. Telegrams: "CYMOZIA, LONDON." MAX KOHL, LTD., Chemnitz, Germany, MANUFACTURERS OF PHYSICAL, CHEMICAL, AND PRECISION_MECHANICAL INSTRUMENTS AND APPARATUS. THE LARGEST ESTABLISHMENT OF ITS KIND. All apparatus described in "An Introduction to Electricity," by Bruno Kolbe, published by Kegan Paul, Trench, Trübner and Co., Ltd., London, 43 Gerrard Street, Sono. SPECIALITY: Acoustical Apparatus, such as pipes, tuning forks, syrens, and all other high precision instruments of this kind which were formerly supplied by Rud. Koenig, Paris, and Appunn, Hanau. One of our college customers in the U.S.A. writes: "I am glad to be able to inform you that the tuning forks which you supplied for the Department of Psychology compare very favourably with ones previously obtained from Landry and Koenig and are possibly superior." Profusely Illustrated Catalogues with 3500 Illustrations, directions, quotations, references, &c., in English, French and German, supplied without any charge to Colleges, Universities and Physicians. World's Fair, St. Louis, 1904, Grand Prize and Gold Medal. World's Fair, Chicago, 1893, 2 Diplomas; World's Fair, Paris, 1900. FIRST AND ONLY MACNALIUM BALANCE IN EXISTENCE. MOST SUITABLE AND SPECIALLY RECOMMENDED FOR STUDENTS' USE. ADVANTAGES OYER THE ORDINARY BRASS BALANCE: Lighter and stronger, always clean and bright, never rusty. Also preferable for use in Laboratories, the Magnalium not being affected by fumes and gases. OBTAINABLE FROM ALL WHOLESALE CHEMICAL AND SCIENTIFIC APPARATUS DEALERS, to whom application should be made for Samples, Prices, and Full Particulars. |