BAIRD &TATLOCK (LONDON) LTD. 



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4366 



4367 



4366 s Adjustable Absorption Tubes, with quartz end plates, 19 mm. clear aperture ; the 

 thickness of the light can be read off in millimetres on the scale 



4367 s Stand to hold spectroscope tubes, with insulated sliding arms and terminals 



4368 s Vacuum Tubes of fused transparent silica for ultra-violet work, with secure mercury seals 



A. Filled with Hydrogen, Oxygen or Nitrogen . . . . . . . . each 



B. ,, Helium or Argon 



C. Neon, Krypton, or Xenon 



D. Unfilled for experimental purposes 



4369 s Sparking Tubes of glass, with gold electrodes and platinum conducting wires, for the spark 

 spectra of metals in solutions, as used by Dr. J. Holmes Pollok (Sec. Proc. Royal Dublin 

 Soc.) . . . . . . . . . . . . . . . . each 



4370 s Prisms for Spectroscopic Work. The following sizes are made in refractive indices 

 from 1.58 to 1.65. They are only supplied in the sizes and of the refractive indices stated. 

 The surfaces are rectangular. 



It will be noted that the lengths of the surfaces in the above prisms are greater than the 

 heights, and that the ratio of length of surface to height becomes greater with the refractive index. 

 By this means a more satisfactory effective aperture is obtained. 



2 2 

 12 



2 10 

 3 5 

 5 8 

 2 5 



16 



CROSS STREET HATTCTN GARDEN, E-C 



812 



