PRACTICAL PAPERS—SUGAR-BEET AND BEET SUGAR. 289 
generally with excellent success, but this method has not as 
yet superseded the more common method of pressure. 
The name given to the process of purification of the juice 
is defecation. The object is to remove, as far as possible, the 
foreign matters remaining in the juice after pressure. These 
are principally nitrogenous matter, mineral substances, color¬ 
ing matter, and the coagulable albumen. The coagulable 
albumen is removed by the action of heat, which causes it to 
become insoluble. To remove the other matters lime is added. 
These form, with the lime, insoluble compounds which are 
easily eliminated, but as an excess of lime combines with the 
sugar and forms saccharate of lime, which causes a loss of su¬ 
gar by its becoming dissolved, and as this saccharate is injuri¬ 
ous to the manufacture of good sugar, being one of the most 
active causes of discoloration in cooking, and its presence pro¬ 
ducing sucre gras, it is necessary to eliminate this access of 
lime. This was formerly done by passing the juice through 
animal charcoal. Mr. Basset* observes that he is ignorant what 
have been the motives which have induced manufacturers to 
make use of this operation, and remarks that the animal char¬ 
coal has no effect on the lime ; that it does not act upon the 
saccharine alkalies ; and that its decolorizing power—the only 
one it possesses—is of no value when the liquid is not free 
from the ulterior causes of the color, i e., the alkaline basis. 
The use of lime in large quantities for the purpose of elimin¬ 
ating the foreign matters contained in the juice has therefore 
been proposed. A solution of saccharate of lime is thereby 
obtained, which is cleared of the lime by passing a current of 
carbonic acid gas, obtained by the combustion of coal through 
it. This is in principle the process which is known to-day 
under the name of carhonation. The carbonic acid acts upon 
the lime, but has no permanent effect upon the alkalies. It is 
true that the saccharate alkalies are decomposed by the car¬ 
bonic acid, but as the alkaline carbonates are not removed, the 
saccharates are again brought together by the heat, and are an 
active cause of coloring and loss. M. Basset recommends the 
♦Etudes eur rExpositiou de 1867, 3© Fascicule, 30juin, 1867. 
