BAIRD &. TATLOCK (LONDON) LTD. 



5025 (Fig. A) 

 5025 s Walpole's Colorimeter 



5025 (Fig. B) 



1 12 i 



5026 s Glass Tubes with glass bottom cemented on, for above, large size . . . . each 



5027 s Glass Tubes with glass bottom cemented on, small size . . . . 



WALPOLE'S COLORIMETER FOR THE TITRATION OF COLOURED FLUIDS 



Consists of a mahogany case with hinged front, and a white opal glass plate at bottom to reflect the light 

 through the two pairs of tubes inside the case. The tubes consist of specially selected pieces of glass tubing of 

 uniform diameter, with a base of clear glass fixed by means of an insoluble cement. 



The light reflected from the white opal glass plate shown in Fig. A passes upward through the glass tubes 

 shown in Fig. B, and the two pairs of tubes can be compared in the ordinary way. It will be seen that in the 

 general case, if the two columns match in colour, and if the upper tubes contain the pigmented fluids, and one 

 of the lower tubes is colourless, the colour of the remaining lower tube will be the difference in colour between thfi 

 two upper tubes. 



An example of the method of working may be described thus : 



Equal quantities, say, 10 cubic centimetres of the coloured fluid are placed in A and B, and an indicator 

 solution is added equally to c and B. In c is placed 10 cubic centimetres of a mixture of standard reaction to 

 which it is desired to titrate. Finally, 10 cubic centimetres of distilled water is placed in D. To the tube B, 

 standard acid or alkali is added till the colours seen looking down the two tubes, match. At that point, the 

 colour due to the indicator in B is the same as that due to the indicator in c. That is to say, the contents of B 

 have now the same reaction as the contents of the standard tube, subject to such corrections the particular 

 case demands. 



Specific examples of the use of this instrument both for titrating' coloured fluids, and for the determination 

 of H ionic concentration by the method of Friedenthal and Salm, as extended by Sorensen, may be found in the 

 following literature : 



G. S. Walpole, Proceedings Physiological Society, vol. xl., 1910, p. 27. 



G. S. Walpole, Biochemical Journal, vol. v., pp. 207-214 



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