CORRESPONDENCE. 235 
Translation. ] Paris, April 20, 1857. 
To M. ALEXANDRE VATTEMARE. 
Srr,—The crystallization of the sugar of the sorghum, it seems, 
should be easily obtained in all cases where the cane can be sufficiently 
ripened ; and as the proportion of the sugar is an unfailing index of 
ripeness, it follows that we could always be sure of obtaining a good 
crystallization of juices whose density exceeds 1:075, while weaker 
ones would not yield satisfactory results after concentration. I 
attribute this peculiarity to the fact that the sugar is preceded in the 
juice by a gummy principle, which seems to be transformed at a late 
date, for its proportion diminishes in exact correspondence with the 
increase of the sugar. The uncrystallizable sugar, or glucose, under- 
goes the same changes; that is to say, it is more abundant before 
than after the complete maturity, but its action seems less prejudicial 
to the progress of crystallization. The gummy principle obstructs it 
in two ways; for, beside being a serious obstacle to the commence- 
ment of crystallization, it afterwards renders it almosta matter of 
impossibility to purge the crystals if obtained. However, as I 
observed, this difficulty only presents itself in the employ of unripe 
canes ; for, as soon as the juices acquire a density of 1-080 and more, 
they contain but little else than crystallizable sugar, and their treatment 
presents no difficulty. The lime employed, even to a slight excess, is 
not detrimental, it seems to me, in practice, as theory would perhaps 
indicate. Perhaps a slight fermentation, which is inevitable, may 
disengage enough carbonic acid to destroy the uncrystallizable com- 
pound formed by its union with the sugar. The fact is, that the best 
crystallizations obtained have been had in those experiments in which 
I feared to have used too much lime. I should remark that heretofore 
my operations have been but on a small scale, and it is necessary to 
be very prudent before applying the experiments of the laboratory to 
practical operations ; but at all events, it seems to me, after all these 
trials, that the crystallization will not meet with serious obstacles where- 
ever the plant attains a complete maturity. 
(Signed) VILMORIN. 
