167 



whole, or, (3) the values given in the table for dry substance from refract- 

 ive index may not be right. 



COMMERCIAL GLUCOSE. 



The two samples examined show the refractive index dry substance 

 higher by 0.27% than the real dry substance. The closeness of these read- 

 ings would tend to disprove the second cause for honey. 



CAKE MOLASSES. 



Seventeen samples were examined. In 3 cases the refractometer dry 

 substance was higher than the true by 0.16%, 0.39%, and 0.59%. In all 

 the rest it was lower by from 0.3S% to 1.53%. The average difference 

 was 0.79%. 



BEET MOLASSES. 



Fifteen samples were examined. In all cases the true dry substance 

 was higher than the refractometer. The difference varied from 0.38% 

 to 1.83%, with an average of 1.08%. When the original substance was di- 

 luted one-half with water, and a reading made on this, the dry substance 

 obtained was doubled. The results showed 5 cases where the refractive 

 index dry substance was higher than the true by from 0.25% to 0.53%. 

 In all other cases, the true was the highest by from 0.39% to 1.62%, with an 

 average of 0.36%. It is seen then by dilution, the average difference be- 

 tween the true dry substance and refractometer has dropped from 1.0S% 

 to 0.36%. The results then are nearer the true dry substance. This 

 comes about by being able to get a clearer field and thereby a closer read- 

 ing. 



However, later work has shown that this dilution with water, even 

 though it has brought the dry substance by refractometer nearer the true 

 dry substance, introduces a serious error. When water is added to 

 molasses there is a contraction in volume. 



This contraction has been taken into account in the construction of 

 specific gravity and refractometer table for pure sugars so that solutions 

 of the latter, whether mixed with water or a sugar syrup, will give the 

 correct percentage of solids either by specific gravity or refractive index. 



The impurities, however, which accompany sugars in solution in mo- 

 lasses, have not only a different specific gravity than sugar, but also a 



