III. METHODS FOR THE DETERMINATION OP SOLUBLE CARBOHY- 

 DRATES IN AGRICULTURAL PRODUCTS, ETC. 



Eighteenth Convention, 1901, Bui. 67. 



Sugar work divided into three parts: Optical methods; chemical 

 methods; special analytical methods. 



Twentieth Convention, 1903, Bui. 81, Cir. 13. 

 An associate referee on molasses was appointed. 



Page 27, to the heading "1. Determination of water" add "and 

 density " ; after (a) insert " Water " ; after " (b) Areometric methods" 

 add "for density and indirect estimation of water". 



Page 28, preceding table, insert the following: 



This method is accurate with liquids containing only soluble carbohydrates. With 

 syrups, molasses, and liquids containing mineral matter the results are only roughly ap- 

 proximate. 



Page 38, insert the following method for ascertaining the amount of 

 copper reduced, as a provisional method: 



(/) METHOD BY DIRECT WEIGHING OF THE CUPROUS OXID. Prepare a Gooch crucible for 

 the filtration by loading it with a felt of asbestos one-fourth inch thick. First thoroughly 

 wash the asbestos with water to remove small particles, then follow successively 10 cc alcohol 

 and 10 cc of ether, and dry the crucible and contents thirty minutes in a water oven at 100 C. 



Collect the precipitated suboxid of copper in the felt as usual, thoroughly wash it with hot 

 water, then with 10 cc of alcohol, and finally with 10 cc of ether. Dry the precipitate thirty 

 minutes in a water oven at 100 C. , cool and weigh it. The weight of cuprous oxid multiplied 

 by 0.888 gives the weight of metallic copper. 



Page 39, Optical methods for the determination of sucrose, omit 

 Clerget's method (page 39) and Creydts' method (page 40), and sub- 

 stitute for them the German official methods, as follows : 



Determination of sucrose and raffinose. This method is not applicable in the presence of 

 optically active bodies other than sucrose and raffinose. Percentages of raffinose less than 

 0.33 can not be determined with certainty by this method. 



Dissolve the normal weight of the material in water, clarify as usual, and dilute to 100 cc. 

 Filter and polarize the filtrate at 20 C. Record the polariscope reading as the direct read- 

 ing or polarization before inversion. 



Take 50 cc of the clarified solution freed from lead, add 25 cc of water in a 100-cc flask, and 

 add little by little, while rotating the flask, 5 cc of hydrochloric acid containing 38.8 per cent 

 of the acid; and heat the contents of the flask, after mixing, on a water bath heated to 70 C. 

 The temperature of the solution in the flask should reach 67 to 70 in two and one-half to 

 three minutes. Maintain a temperature of as nearly 69 as possible during seven to seven 

 and one-half minutes, making a total time of heating of ten minutes. Remove the flask and 

 cool the contents rapidly to 20 C., and dilute the solution to 100 cc. Polarize this solution in 

 a tube provided with a lateral branch and a water jacket passing a current of water around 

 the tube to maintain a temperature of 20 C. 



Multiply the invert reading, made at 20 C., by 2. If a preliminary calculation using the 

 formula, 



0.7538 X (algebraic difference of the direct and invert readings) =per cent sucrose, 



