48 PROVISIONAL METHODS FOR ANALYSIS OF FOODS. 



11. DETERMINATION OF CANE SUGAR. 



Use Clerget's formula: 



s _(ab] 100 



144- 1 



where $=per cent of cane sugar, adirect polarization, 6=invert polarization, 

 2=temperature. 



12. DETERMINATION OF COMMERCIAL GLUCOSE IN MOLASSES, SIRUPS, AND HONEY. a 



As to preliminary indications of the presence of commercial glucose in these prod- 

 ucts, a sample of molasses of light color whose normal weight made up to 100 cc 

 and polarized in a 200-mm tube shows a reading much in excess of 60 on the cane- 

 sugar scale is almost sure to contain commercial glucose, while a dark-colored sample 

 of molasses should, if pure, polarize considerably below 50 C. A sample of maple 

 sirup which polarizes much in excess of 65 C on the cane-sugar scale is to be sus- 

 pected of containing commercial glucose, while a sample of honey that polarizes to the 

 right of the zero point is apt to be adulterated either with cane sugar or commercial 

 glucose or both. If any of these products show an invert reading much to the right 

 of the zero point, commercial glucose is almost sure to be present. 



It is manifestly impossible to determine with absolute accuracy the amount of 

 commercial glucose present by reason of the varying amount of dextrine, maltose, 

 and dextrose present in the adulterant. It is possible, however, in molasses and 

 maple sirup, wherein the amount of invert sugar is so small as not to appreciably 

 affect the result, to estimate approximately the amount of commercial glucose by the 

 following formula: 



(a-S) 100 

 175" 



where G = per cent of commercial glucose, a direct polarization, S= per cent of 

 cane sugar. 



In honey, which is composed largely of invert sugar, much closer results are 

 attained by first inverting the sample and obtaining the polariscopic reading at 87 

 in a tube surrounded by hot water. This reading divided by 175 gives the approxi- 

 mate percentage of commercial glucose in the sample. 



A large number of samples of commercial glucose have been procured by the 

 department of food and drug inspection of the Massachusetts Board of Health 

 directly from various manufacturers of compound or adulterated honey, molasses, 

 and sirup, to ascertain the grade used by them for this purpose. AR a result of 

 this investigation, it has been found that the grade best adapted by its consistency 

 for admixture with these products, and, indeed, the grade largely, if not univer- 

 sally, used for this purpose, has a density of about 42 Beaume and polarizes on 

 the cane-sugar scale at or about 175 (26.048 grams made up to 100 cc and polarized 

 in a 200-mm tube with the Schmidt & Haensch instrument). From repeated experi- 

 ments made in the writer's laboratory on mixtures containing known proportions of 

 commercial glucose, 175 has been adopted as the most satisfactory factor and has 

 been found to give a very close approximation. b 



"Leach, 32d An. Kept. Mass. State Board of Health, 1900, p. 658. Reprint, p. 42. 



b Among the samples of commercial glucose examined were several obtained from manufacturers 

 of compound jellies and jams, and the examination of these would seem to show that the grade used 

 mostly for this purpose polarizes at or about 150 C. If this is verified, 150 instead of 175 should be 

 used in the above formula when applied to jellies and jams. Theeffectof high temperatures employed 

 in the preparation of this class of goods should not be lost sight of, a factor that does not enter in to 

 disturb the application of the method to adulterated molasses, sirups, and honeys which are mixed 

 in the cold. 



For chewing gum a grade of commercial glucose is used polarizing at about 185. 



