:cxli 



NA TURE 



[October 19, 1905 



SPECIAL NOTICE TO LABORATORIES AND HOSPITALS. 



For convenience in Stocktaking -we are prepared to offer 



3 LARGE INDUCTION COILS 



(of 18 to 24-inch continuous spark) 

 at a VERY CONSIDERABLE REDUCTION off regular prices. 



Variable Conde 



eavy spark of over the length indicated, are most completely fitted, including Variable Primary and 

 11 Interrupter, Commutator, and Discharging Pillars, and may be seen and tested at any time 

 our own highest class workmanship throughout, and similar to those supplied to the leading 

 and Hospitals, and giving the greatest satisfaction under heavy daily work, 



I'lnriiKji I'AHTivui^Aits o\ ifri.ifArioy. 



U A Diyy/ \A# /^(T^'V 1 +rJ ACTUAL MAKERS of X Ray, &c.. Apparatus to the Admiralty, 

 n>nl\r% ¥ W ■ w\^yVj LLUi] War Office, Colonial Office. Indian Government. &c. 



la ROSEBER Y AVENUE, & 15-21 LAYSTALL STREET, LOIMPON, E.C. 



~"" ^ NEW 



^J^ Patent Tube 



NEON, KRYPTON, XENON, 



also 



ARGON, HELIUM. 



We have now in stock a number of 



Vacuum Tubes of the above Gases, 



GUARANTEED PURE. 



AOA]VI MILGER, Lta., 



75a Camden Road, London, N.W. 



AWARDED GOLD MEDAL. ST. LOUIS EXHIBITION. 1904. 



SPECTRUM 



supply the 

 filled with Neoi 

 Krypton, and 



Xenon. 



ANALYSIS. 



Specially adapted for ihe New Gases 

 Argon, Helium. &c., either singly or in 

 combination. Shows the Spectrum of 

 any Gas to a degree never hejore 



attainable. 



ILLUSTRATED PRICE LIST OF SPECTROSCOPES. &c., POST 

 FREE ON APPLICATION. 



RARE 



CHEMICALS 



METALS 



MINERALS 



For Laboratory, Scientific, and all other 

 purposes. 



RADIUM SALTS & RADIO-ACTIVE PREPARATIONS. 

 CALCIUM METAL. 1/6 oz.; 20 - lb. 



"Price List on Application. 



HARRINGTON BROS., 



r/,,„ii<<il .V,ii,li;„rl,ir<i:t iiikI l><ilUrs. 



4 OLIVERS YARD, CITY ROAD, LONDON, E.C. 

 JAMES SWIFT & SON'S 



NEW PAN-APLANATIC OBJECTIVES 



OF THE HIGHEST POSSIBLE OPTICAL EXCELLENCE. 

 Apochromatics. 



3*" See euloKistic report after test, Nature. March o, 

 page 448. 



A. GALLENKAMP & CO., LTD., 



19 & 21 SUN STREET. FINSEURY SQUARE, LONDON. E.C. 



SPECTRUM TUBES. 



Carbon Dio 



" H" form ... 

 ■Phicker" f< 

 Sealed tubes. 



We are actual makers of Spectrum 



Tubes They are made in the 



"riixlier' form and in "H" form 



(as illustrated). 



ning Hydrogen, Oxygen. Water Vapour, Nitroge 

 .. ■ "'ercury, and Hydrogen and Mercury. 



66 each. 



A. C. COSSOR, 54 Farringdon Road, London, E.C. 



Gold Medal Awarded, St. Louis Exhibition, 1904. 



Telephone, 10547 Central. 



iwiiCFSoscoB'ic siL<ir>E:s 



MARINE ORGANISMS, Hydro.oa, Crustacea, Annelida Sc, polyps 



extended, without pressure, dark ground or opaque. T<yv beantiful. List. 



f',l^.!l?r,Vi''°"P* "'' Diatoms, Pelrological. Sc 'Dispersal of Mr. 



HORNILLL'S collection of Slides. Marine and Botanical, from 5,/. each. 



IVIXCXIOSCOPE:s. dec 



SECOND-HAND, large and ever-changing stock. Edinburgh H. 

 with Binocular and -Monocular bodies, others including Objectives, Con- 

 densers, Polariscopes, &c., by Watson, Ross, Powell and Lealand, Beck, 

 Pillischer, Reichert, Leitz, &c. Prismatic Binoculars, Lantern Slides, 

 Mountina Materials. Lists. 



Mr. HERBERT CLARKE, 104 LEADENHALL STREET, LONDON 

 Tel. :— 13,6 Central. 



UNIVERSITY OPTICAL ■WORKS. 



81 Tottenham Court Road, London. 



HOPKIN & WILLIAMS, Ltd. 



16 CROSS STREET, HATTON GARDEN, LONDON, E.C. 



Works-U.FORD , E. 



PURE CHEMICALS 



For TEACHING, RESEARCH, and TECHNOLOGY. 



