October 12, 1905] 



NA TURE 



VOQEL'S 

 SPECTROGRAPH. 



Two prisms of dense flint-jjiass enclosed 

 in a strong brass case, to which the colli- 

 mator and the camera are attached ; 

 collimator of i|in. aperture and i8in. focal 

 length, with adjustable slit with micrometer- 

 screw and dividing drum ; the camera is 

 furnished with an achromatic double 

 objective of 2in. aperture and r^gm. focal 

 length ; size of plate, 7nin. by 5m. 



Can he seen at my Showocms 

 as below- 



DELIVERY FROM STOCK. 



PETER HEELE, 



115 HIGH HOLBORN, 



LONDON, W.C. 



Maker df Physical, Chemical, and 



other Instruments, and every kind of 



Spectroscope and Polarimeters. 



GRAND PRIX, PARI5, 1900; ST. LOUIS, 1904. 

 Telegrams: "ARCTITUDE, LONDON." 



BRADY & MARTIN, LTD., 



NEWCASTLE-UPON-TYNE. 



Makers of 



SODEAU'S GAS ANALYSIS 

 APPARATUS. 



See Journal of Society of Chemical Industry, February 28, 

 1903, p. 187.) 



GENERAL CHEMICAL APPARATUS FOR COLLEGES, 

 SCHOOLS AND WORKS LABORATORIES. 



Dr. Henry Stroud's Pattern. 



Apparatus for General 



Demonstration and Experiments 



in Physics. 



METEOROLOGICAL APPAR/VTUS. 



PURE CHEMICALS AND REAGENTS. 

 STANDARD SOLUTIONS. 



stains for Bacteriolog^ical and 

 Microscopic Work. 



RADIUM 



OF 



1,800,000 



ACTIVITY. 



We have just received a limited 



consig-nment of the above, and are open 



to supply same in 5 mg-. tubes at a 



REASONABLE PRICE. 

 W. IVIARTINDALE, 



Manufacturing Chemist, 



10 NEW CAVENDISH STREET, LONDON, W. 



