169 
Summarizing the average results, we find that the refractometer dry 
substance is higher than the true. 
Per Cent. 
ithe ditkerence: in case of maple Syrup. <<... 2% «<6. 0.50 
Mes a@ifterence: il "GaSe! Of Cane SYIUP) o....00- 2.222556 0.29 
hey qufkerence. im Case OL NONCYS®. 2: = ses sce csoe- =< Seven eae 
dither @ditterence-incasey Of, GIWICOSe ee «eis teria) «<< << elerle © 0.27 
The difference in case of cane molasses ............... 0.79 
The difference in case of beet molasses ............... 1.08 
The difference in case of beet molasses (half) ........ 0.36 
With the exception of the honeys and possibly cane molasses, also 
beet molasses undiluted, the differences are well within the error of deter- 
mination of water by actual drying. By half dilution, the beet molasses 
is brought within the limits, and wuiere dilution with sugar solution tried 
this difference would be cut down considerably. Cane molasses, showing 
0.79%, might be considered within the limits, as a true moisture content 
on this material is a difficult task. Honeys are, then, the only ones whose 
difference is large, but it is hoped that with the work now being carried 
on, the reason for this difference will be obtained and a method for pro- 
cedure be established for this grade of substance. However, there is one 
thing to be said in regard to the refractometer, that it is possible to ob- 
tain duplicate results that are identical, and different investigators should 
obtain identical results, which is a condition that does not exist with the 
other methods for dry substance determination in use now. The refracto- 
meter method has the advantage of being quick and not losing accuracy 
by speed, and then only small portions are necessary for a determination. 
The method of making a dry substance determination is substantially 
this: The instrument (Fig. 1) is placed so that the light falls on the mir- 
ror (R) and this is turned on its axis to reflect the light up through the 
prism (B) and (A). The source of light can be daylight, but a better 
one is a 82 or higher candle power lamp. The tubular (D) is connected 
by rubber tubing to the source of water supply of constant temperature 
and the other tubular (E) has a rubber overflow connection. The ther- 
mometer is placed in its socket. The optical parts of the instrument are 
turned forward on the stand (a). By turning the catch (V) the prism 
B is swung open on (C) from prism (A) and a few drops of the solution 
to be examined is placed on the prism (A). Enough of the solution should 
be added so that on closing the prism (B) on (A) a part of the liquid is 
forced out. The optical parts are brought back into their original place. 
