181 



man's test,a as it is called, one can distinguish between these dextrins, and hence 

 ;ui say whether commercial glucose has been added. Browne called attention 

 to the importance of this test. He also gave methods for the determination of the 

 perrenta-e ,,f -rlurose present in mixtures. In the following table are given analyses 

 of mixtures .if different amounts of glucose and honey: 



Analyses of mixtures of commercial glucose and clover honey. 



In the direct and invert polarizations it is noted that there is a gradual change from 

 a "plus" polarization to a "minus" polarization, due to the increase of the glucose 

 { n outages. With reducing sugars before and after inversion there is again a large 

 inrrease with the decrease of glucose. The difference in polarization of the inverted 

 solution at 20 and 87, as shown in column 4, increases from 8.14 to 28.05. C. A. 

 Browne found that nearly 95 per cent of his samples of pure honey showed a difference 

 rangn >aml the lowest was about 20. Taking 23 as a low figure, a mixture 



"i I" |"T i -i -tit 'f -jlurose with honey would not be considered adulterated. If, how- 

 ever, the natural honey had not shown such a high difference, viz, 28.05, then 10 per 

 rent would be easily detected by this figure; but by adding up to 5 per cent this 

 difference is not noticeable, and also the other analytical figures would not indicate 

 the presence of glucose. It is, however, easily distinguishable when Beckman's test 

 is applied t> the honey In fact, with the addition of as low as 1 per cent of glucose, 

 its presence .an I.e recognized by this test, especially if the dextrins are precipitated 

 by alrohol and then <li>sol\ed in water, thereby concentrating them. 



In the la.^t three columns of the table the results of determining per cents of glucose 

 by the three different methods are given. It is seen that the method proposed by 

 Browne gives the figures closest to the actual mixture. Obviously in honey work 

 Beckman's test should l>e employed in all cases, and in the hands of ordinary chemists 

 after a few trials it will give good results. 



As to the need for such a test, it is a well-known fact that where commercial 

 insert su-ar is used in a mixture of honey, also where honeys that crystallize are 

 used, a small percentage of glucose is quite often added to prevent this crystallization. 

 Cases are on record of such mixtures where less than 1 per cent of glucose was added. 

 The ii Klin test will indicate the presence of glucose down to that amount. 



A I 'ii LT this line the same question comes up in the examination of sirup and molasses. 

 As is well known, glucose is added to these products in large quantities, and again in 



aZts. anal. Them., 1896, 35 : 267. 



