40 



BULLETIN 466, L T . S. DEPARTMENT OF AGRICULTURE. 



In this method specially standardized 100 cc flasks are used. 

 Upon their necks are etched marks showing where 100 grams of 

 recently boiled distilled water reach, at a temperature of 17.5° C. 

 The correctness of all readings depends on this graduation. 



Twenty grams of the sample are weighed and transferred with 

 water to one of these flasks. The sugar is dissolved by shaking, 

 and the flask, after being filled almost to the mark with water, is 

 allowed to stand in a constant temperature bath for 20 or 30 minutes 

 with occasional shaking. The volume is then completed with water 

 of the same temperature, the solution shaken, and a reading taken 

 with the immersion refractometer, the temperature being noted at 

 the same time with an accurate thermometer (better calibrated to 

 one- tenth). If the temperature is any other than 17.5° C, the reading 

 obtained must be corrected by the figures opposite the temperature 

 in Table XXVI. For readings taken at temperatures below 17.5° C. 

 the correction is subtracted, and for readings at temperatures above 

 17.5° C. the correction is added. 





Table XXVI. — Temperature corrections. 1 





Tem- 



Num- 

 ber to 



Tem- 



Num- 

 ber to 



Tem- 



Num- 

 ber to 



Tem- 



Num- 

 ber to 



pera- 

 ture. 



be sub- 

 tracted. 



pera- 

 ture. 



be 

 added. 



pera- 

 ture . 



be 

 added. 



. pera- 

 ture. 



be 

 added. 



° C. 





° C. 





"C. 





"C. 





15.0 



0.72 



17.6 



0.03 



20.2 



0.82 



22.8 



1.62 



15.1 



.70 



17.7 



.06 



20.3 



.85 



22.9 



1.65 



15.2 



.67 



17.8 



.09 



20.4 



.88 







15.3 



.64 



17.9 



.12 



20.5 



.91 



23.0 



1.69 



15.4 



.61 







20.6 



.94 



23.1 



1.72 



15.5 



.58 



18.0 



.15 



20.7 



.97 



23.2 



1.75 



15.6 



.55 



18.1 



.18 



20.8 



1.00 



23.3 



1.78 



15.7 



.52 



18.2 



.21 



20.9 



1.03 



23.4 



1.81 



15.8 



.49 



18.3 



.24 







23.5 



1.85 



15.9 



.46 



18.4 



.27 



21.0 



1.06 



23.6 



l.as 







18.5 



.30 



21.1 



1.09 



23.7 



1.91 



16.0 



.44 



18.6 



.33 



21.2 



1.12 



23.8 



1.96 



16.1 



.41 



18.7 



.36 



21.3 



1.15 



23.9 



1.99 



16.2 



.38 



18.8 



.39 



21.4 



1.18 







16.3 



.35 



18.9 



.42 



21.5 



1.22 



24.0 



2.03 



16.4 



.32 







21.6 



1.25 



24.1 



2.06 



16.5 



.29 



19.0 



.45 



21.7 



1.28 



24.2 



2.09 



16.6 



.26 



19.1 



.48 



21.8 



1.31 



24.3 



2.12 



16.7 



.23 



19.2 



.51 



21.9 



1.34 



24.4 



2.15 



16.8 



.20 



19.3 



.54 







24.5 



2.19 



16.9 



.17 



19.4 



.57 



22.0 



1.37 



24.6 



2.22 







19.5 



.61 



22.1 



1.41 



24.7 



2.25 



17.0 



.15 



19.6 



.64 



22.2 



1.44 



24.8 



2.29 



17.1 



.12 



19.7 



.67 



22.3 



1.47 



24.9 



2.32 



17.2 



.09 



19.8 



.70 



22.4 



1.50 







17.3 



.06 



19.9 



.73 



22.5 



1.53 



25.0 



2.35 



17.4 



.03 







22.6 



1.56 



25.1 



2.38 



17.5 



.00 



20.0 



.76 



22.7 



1.59 



25.2 



2.42 







20.1 



.79 







25.3 



2.45 



Stanek, Zeit. Zuckerind. Bohmen, 35 (1911), p. 187. 



The percentage of the dry substance is then obtained from Table 

 XXVII. 



