e^^ 



BAIRD &TATLOCK (LONDON) LTD. 



Fig. 3- 



Fig. I. Figs. 456. 



5032-5033 5032-5033 



5032 s Dubosq Colorimeter, without vernier 

 5033 s Dubosq Colorimeter, with vernier 



DESCRIPTION. 



Fig. i. Represents front view of apparatus. When in use the operator stands behind. 



Fig. 2. Represents back view, and shows the divisions and the vernier. 



Fig. 3. The path of the light inside the instrument. 



Fig. 4. Shows the appearance of the diaphragm seen through the eyepiece when the apparatus is regulated to zero. 



Fig. 5. Shows the same in use as Fig. 6 when an equality of tones has been obtained. 



THE PATH OF THE LIGHT (Fig. 3). 



The diffused light from a lamp or a monochromatic burner, after being reflected on to a mirror A, is separated 

 into two beams, which penetrate respectively into the two tubes B, B. The right beam is reflected twice in the 

 right half of prism K, penetrating into the eyepiece, it only affects the right half of the field ; the left beam does 

 exactly similar, affecting only the left side of the field. 



No bright light is needed ; it is sometimes better to place before the mirror A a piece of ground glass. (A piece 

 is supplied.) 



INSTRUCTIONS FOR USING. 



This instrument gives relative results. 



Place standard coloured liquid in left tube B. 



Place liquid to be compared in right tube B. 



Now lower the right tube D until it reaches what appears to be the most convenient point for estimation, 

 which depends on the colour of the liquids ; now note the divisions on scale corresponding to the standard liquid. 



Lower the tubes D till they touch the bottom of B and the verniers g mark zero. 



Look through o, and then gradually move the apparatus till both half fields are equally illuminated ; now 

 move screws E till equality of tone is produced. For two liquids the colour is inversely proportional to the density 

 of the column of liquid traversed by the light and proportional to the quantity of dissolved matter. 



Example. Suppose a liquid gives a reading of I2 m 5, and the standard is io m , we shall then have the following 

 proportion : 



Colour of liquid _ height of standard _ io m 



Colour of standard height of liquid I2'"5 ~ ' ' 



so the colour of the standard being represented by I, that of the liquid will be 0.8 



To Clear Tubes B, 



Raise pistons D, take out tube B, unscrew ring c, take off the glass at bottom. The rest can be easily cleaned 

 by means of a fine cloth. 



10 

 12 



) 







CROSS, STREET HATTOTST GARDETST, E-C 



920 



