CANE SUGAK. 



within the dust-proof casing G is contained the system of quartz wedges 

 forming the compensator ; FIB the telescope which focusses the field of vision; 

 in the enlarged part of F, i.e., between the letters F and G is the analyser ; 

 M is a telescope whereby the scale is read, it being illuminated from the lamp 

 light passing through the aperture in the light shield at . The pattern 

 shown is a double wedge compensating instrument, the milled head controlling 

 the working wedge being seen at A ; the extension of this to the table saves 

 much fatigue where many consecutive analyses are made. 



The pattern adopted by Peters is shown in Fig. 238 ; in arrangement of 

 parts it is nearly identical with the pattern adopted by Schmidt & Haensch. 

 The instruments made by Messrs. J. & J. Pric (Fig. 239} are also similar 

 to the above in arrangement of the optical parts ; the scale illumination is, 



FIG. 238. 



however, made differently. Within the body of the instrument, next 

 to the source of light, is a reflector, inclined at 45 ; a diaphragm therein 

 allows light to pass on to the polarizer ; the other part of the light is 

 reflected to a vertical silvered mirror which throws a pencil of light on 

 the scale. 



Adjustable Landholt-Lippich Polariscope. 8 As usually 

 made, these instruments, when designed specially for saccharimeters, have a 

 fixed half shadow angle ; the smaller the half shadow angle the less is the 

 intensity of light, and the greater is the delicacy of the instrument ; very 

 light-coloured solutions can be read with a low intensity of light, but for dark- 

 coloured solutions it is often advisable to increase the half shadow angle, and 



436 



