SUGAR, MOLASSES, CONFECTIONS, AND HONEY. 647 



ment. The weighing of the sugar, 26.048 grams, was made on a balance indicating 

 tenths of a milligram. The sample was dissolved in distilled water at 17.5 C. and 

 made up to 100 cc in a flask graduated to contain 100 05 grams of pure water at 17.5 

 C. The polariscope having been correctly set at zero, the above sugar solution polar- 

 ized in 



The 100 mm tube 49.9 



The 200 mm tube 99.9 



Composition and standardizing of Fehling's solution. The Fehling's solution used was 

 prepared according to the following formula : 



Sulphate of copper, cryst 34.639 g in 500 cc of water. 



Rochelle salts 173.000 g in 400 cc of water. 



. Sodium hydrate 50.000 g in 100 cc of water. 



To standardize this solution the test sugar sent by the Department was used. 

 Of this there was weighed out 0.9500 gram. This was dissolved in about 75 cc of 

 distilled water, 2.5 cc. concentrated C. P. hydrochloric acid were added, the mixture 

 warmed up to 68 C. and kept for five minutes at between 68 and 70 C. 



The flask with its contents was then quickly cooled, the solution was neutralized 

 with sodium carbonate, and then made up to 100 cc. Of this solution exactly 5.0 cc 

 were required to precipitate all of the copper in 10 cc of the above Fehling solution. 

 10 cc Fehliug solution contain 0.0877 copper. 



5 cc of the above invert sugar solution contain 0.050 grams invert sugar.* 

 As 0.0877 copper were precipitated by 0.050 invert sugar, 



0.0877 - 0.05 = 1.754 



that is, the ratio of invert sugar to copper is as 1 : 1.754 with a 1 per cent solution of 

 invert sugar. 



PREPARATION OF SOLUTIONS FOR POLARIZATION. 



Polarizations. Whenever possible the solutions were prepared for polarization 

 solely by addition of basic acetate of lead, together with a few drops of acetic acid. 

 In numerous instances, however, in the analysis of confections honeys and molasses 

 the addition of two to three cubic centimeters of alumina cream was found to be 

 indispensable. 



With many of the confections, sirup, and molasses samples, dry blood carbon had 

 also to be used in order to effect decolorization. This carbon was perfectly dry and 

 always added after making the solution up to 100 cc. All readings in the polariscope 

 were made at 20 C., and the observations were in most instances made by two 

 observers. 



Polarization after inversion. The inversion was made on 50 cc of the solution used 

 for the direct polarization. The inversion was effected by the addition of 5 cc of 

 concentrated hydrochloric acid ; the solution, about 75 cc in volume, was heated to 

 between 67 and 68 and kept at that temperature for five minutes. It was then 

 quickly cooled, made up to 100 cc, and some of this solution was placed in an obser- 

 vation tube piovided with a thermomef er and the reading taken at 20 C. 



Sucrose. The following is the calculation by which the sucrose was found wher- 

 ever recorded. 



e 100S 



Sucrose = 14a . 66 _ i< . 



S = Bum of the two polarizations of the normal weight solution, before and after 

 inversion, the minus sign being neglected. 



t = temperature in degrees C. at which the polarization of the inverted solution 

 was observed. In all of the analyses here reported, =20 C. 



* 95 sucrose correspond to 100 invert sugar. (U. S. Department of Agriculture, 

 Division of Chemistry, Bulletin No. 24, p. 199.) If 0.9500 grams sucrose are dis- 

 solved up to 100 cc, 1 cubic centimeter ^=0.01 grams invert-sugar, and 5 cubic centi- 

 meters 0.05 grams invert sugar. 



