122 METHODS OF ANALYSIS [Chap. 



Place 6-7 grams of the prepared sand and a short stirring rod in a flat-bottomed 

 dish. Dry thoroughly, cool in a desiccator, and weigh. Then add 3-4 grams of 

 the molasses, mix with the sand (if necessary to thoroughly incorporate the two, 

 add a little water), dry in a water oven at the temperature of boiling water 

 for 8-10 hours, stirring at intervals of an hour, cool in a desiccator, and weigh. 

 Stir, heat again for an hour, cool, and weigh. Repeat the heating and weighing 

 until the loss of water in an hour is not greater than 3 mg. '' 



AREOMETRIC METHODS. 



(Not applicable to low-grade sugar products, molasses and other materials 

 containing large amounts of non-sugar solids.) 



SPECIFIC GRAVITY, WATER AND TOTAL SOLIDS. 

 5 By Means of a Spindle.— Official. 



The density of juices, sirups, etc., is most conveniently determined by means 

 of the Brix hydrometer. For rough work, or where less accuracy is desired, the 

 Baum6 hydrometer may be used. The Brix spindle should be graduated to tenths. 

 The range of degrees recorded by each individual spindle should be as limited as 

 possible. The solution should be as nearly as practicable of the same tempera- 

 ture as the air at the time of reading, and, if the variation from the temperature 

 of the graduation of the spindle amounts to more than 1°, a correction must be 

 applied according to the table under 6. Before taking the density of a juice, allow 

 it to stand in the cylinder until all air bubbles have escaped, and until all fatty or 

 waxy matter has come to the surface and been skimmed off. The cylinder should 

 be large enough in diameter to allow the hydrometer to come to rest without touch- 

 ing the sides. A table of specific gravities at .. " and per cent by weight of suc- 

 rose is given under 9, and a table for the comparison of specific gravities at ^^g. ', 

 degrees Brix (per cent by weight of sucrose), and degree Baum6 is given under 8. 



If the sample is too dense to determine the density directly, dilute a weighed 

 portion with a weighed quantity of water, or dissolve a weighed portion and dilute 

 to a known volume with water. 



In the first instance the per cent of total solids is calculated by the following 

 formula: 



WS 



Per cent of solids in the undiluted material = — in which 



w 



S = per cent of solids in the diluted material; 



W = weight of the diluted material; 



w = weight of the sample taken for dilution. 



When the dilution is made to a definite volume, the following formula is to be 

 used: 



Per cent of solids in the undiluted material = „, in which 



W 



V = volume of the diluted solution at a given temperature; 



D = specific gravity of the diluted solution at the same temperature; 



S = per cent of solids in the diluted solution at the same temperature; 



W = weight of the sample taken for dilution at the same temperature. 



If the spindle reading be made at any other temperature than 17.5°C., the re- 

 sult should be corrected according to the following: 



