216 SORGHUM. 



siderable experiment, but at the j^resent time the exact effect of each 

 imparity is not known. 



The average of tliirty-four analyses of sorghum juices, made in this 

 laboratory, shows aa average percentage of ash equal to 1.06; the 

 maximum being 1.66 per cent, and the minimum being .82 per cent. 

 We may, then, safely estimate the ash as being about one per cent of 

 the juice. 



Now, while all authorities are agreed as to the melassigeuic effect of 

 certain of the mineral constituents of tlie ash, there is much difference 

 as to the action of other mineral matters ; and while some of these are 

 regarded as quite indifferent in their action, other constituents of the 

 ash are shown to strongly favor the crystallization of the sugar. For 

 example, potassium carbonate increases the quantity of molasses pro- 

 duced, potassium sulphate appears to have no effect, while magnesium 

 sulphate seems to favor the crystallization of sugar, and thus decrease 

 the amount of molasses. 



It is highly pr(jbable, that much of the good effect attributed to the 

 use of suljjhurous acid, as an aid in the crystallization of syrups, is due 

 to the fact, that it converts the harmful alkaline carbonates into the 

 inert sulphates. In the reports of my work, I, in accordance with a 

 common practice among sugar makers, made use of the so-called " ex- 

 ponent," which represented the relative purity of the different juices. 

 This " exponent" was the percentage of sucrose in the total solids of 

 the juice ; and this represented the percentage of the sugar present in 

 the juice, which could be in jiractice obtained as sugar. While this 

 method of calculation is doubtless, at least approximately, correct, when 

 applied to those juices which are generally worked up for sugar, it is 

 obviously erroneous when applied to juices poor in sugar, and with 

 comparatively large amounts of other solids. 



I have, therefore, adopted a method for calculating the available 

 sugar, viz.: — the diflerence between the per cent of sucrose and the sum 

 of the per cents of glucose and solids not sugar, and although confident 

 that all the experiments of Marschall, La Grange, and other?, go to 

 prove that the amount of available sugar thus shown is beyond question 

 too low, it is at least safe to err upon this side rather than the other. 



If we apply these two methods to two specimens of juice, one good 

 and the other poor, it will be seen that for the good juice, the two 

 methods approximately agree, while for the poor juice, they differ 

 widely, and there is no doubt but that the method of the exponent is 

 in such a case inapplicable; e. g.: 



Juice A contains, sucrose, 3.51 per cent; glucose, 4.50 per cent; sol- 

 ids, 1.78 per cent. The exponent would be 35.85, and the available 



