THE POLARISCOPE AS APPLIED TO SUGAR ANALYSIS. 



these factors should be used in place of the normal weight, taken here as 

 26 grms. per 100 true cc. : 



Corrected Normal 

 Weight. 



Polariscope reading 

 in 20 cm. tube. 



Polariscope reading 

 in 20 cm. tube. 



Corrected Normal 

 Weight. 



5 



10 

 15 

 20 

 25 

 30 

 35 

 40 

 45 

 50 



25-90 

 25-92 

 25-93 

 25-94 

 25-94 

 25-94 

 25-95 

 25-95 

 25-95 

 25-96 



55 

 60 

 65 

 70 

 75 

 80 

 85 

 90 

 95 

 100 



25-96 

 25-97 

 25-97 

 25-97 

 25-98 

 25-98 

 25-99 

 25-99 

 25-99 

 26-00 



Control of Scale. Quartz plates, the exact value of which has 

 been determined in sugar degrees, may be obtained from makers. These plates 

 are standardized at 20C. in Europe, and as they are equally affected by 

 variation of temperature with the quartz wedge they will serve at any 



FIG. 251. 



temperature to control the scale of a polariscope of this type ; but if used to 

 control the scale of a polariscope compensating by rotation of the analyser, the 

 correction for temperature must be applied. 



A control observation tube by Schmidt and Haensch is shown in Fig. 253 '; 

 it consists of an outer tube, T, in which is moved by means of a rack and pinion 

 gear the tube /, fitting closely into T, exit of liquid between T and / being 

 prevented by the washer e ; the tube / is closed by a glass disc at c. The 

 solution to be used for testing is poured into the funnel a, whence it fills the 

 tube T. The distance between d and e is regulated by the rack and pinion 

 gear, the exact distance and also the length of the column of liquid being read 

 off a scale carrying a vernier ; the tube is conveniently filled with a solution 

 of the normal weight of sugar in 100 cc. ; with a column of liquid 20 cm. 

 long a reading of 100 should be obtained, and other readings should be pro- 

 portional to the length of the column of liquid. A very rapid control over 



443 



