NEGEETTf AND ZAifBKA, HOLBOBN VIADUCT, E.G., 



FIG. 1055. 



1054 Tourmaline Polariscope, a frame, having a revolving disc carrying a series 



of Crystals, which may be successively brought between the Tourmalines ; 

 each of the latter can be made to revolve in its own plane, and thus place 

 their axes parallel or perpendicular to each other at pleasure, and vary 

 the phenomena of each crystal 4 10 



1055 Soleil's Polariscope or Saccharometer, improved by 



Duboscq, for estimating the value of fluids, &c., with 



the most recent improvements (fig. 1055) ... 16 



1056 Laurent's New Shadow Polarising Saccharometer, having two series 



of divisions, one for the percentage of Sugar, and the other graduated 

 for general Laboratory Work. Complete with one Gas Burner, fitted 

 with two Jets, three Glass Tubes, &c., &c., mounted on a Bronzed 

 Adjusting Stand Price hi Box 18 



1057 Ditto, ditto, of the most complete form, having all 



recent improvements, Gas Burner with two Jets, 



four Glass Tubes, &c., (fig. 1057) Price in Box 30 



This Saccharometer is of much greater accuracy than previous arrangements, 

 and is now adopted by the French Government. In ordering the Saccharometer 

 the approximate pressure of Gas to be used should be stated. 



1058 Eolipyle. If Gas is not available, or if the pressure be feeble and irregular, 



it is advisable to use the Eolipyle, burning Spirit instead of Gas. 



(fig. 1058) Price . .330 



Instructions for use are sent with each instrument. 



1059 Double Image Prism, Selenite Disc of equal thickness, and Three-hole Slider 



for ditto, for showing the production of white light by the union of the 

 complementary colours 110 



1060 Unannealed Glass, various shapes, for showing the 



permanent polarising structure of glass that has been 



uniformly heated and suddenly cooled ... 056 



