Filter and Prepared Charcoal of M. Dumont. 349 



erty of modifying or weakening the action of those substances con- 

 tained In the syrup which are capable of reacting upon the sugar 

 during the boiling. He, therefore, advises the filtration of a third 

 or fourth quantity of syrup through the sarae charcoal, persuaded that 

 afterward they may be crystallized much more readily. 



Long experience only can demonstrate the value of this opinion; 

 we can, however, cite one fact which appears to confirm it. A 

 syrup of beets which had passed through a partially exhausted char- 

 coal without losing any of its dark color, took the fire much better and 

 crystallized more readily than a portion of the same syrup unfiltered. 



M. Dumont's filters are of different sizes. The small contain 

 from twelve to fifteen pounds of charcoal, and the large as much as 

 two hundred pounds. By them, syrups of all densities from the least 

 to the greatest, may be filtered. 



Syrup of 28° to 30° of the areometer filters very well cold, 

 those of 36° to 38° require to be poured in hot, and the charcoal 

 coarser, as before stated, the operation lasts about the same time, but 

 the product is not so well decolorized. 



The syrup of twelve hundred pounds of sugar can be filtered in 

 twenty four hours. 



Why are the syrups filtered by M. Dumont more decolorized than 

 those operated upon the old process ? Several reasons can be assign- 

 ed in reply. It is easy to conceive, that syrup, in passing through 

 the different layers of the column of charcoal should deposit a por- 

 tion of its coloring matter in each layer, thus producing greater effect 

 than in the broad and shallow filters used in the old process. Be- 

 sides, it is not improbable that the ebullition of a syrup with charcoal 

 counterbalances, in part, the decolorizing action of the agent ; per- 

 haps the caloric effects a reaction of charcoal upon the syrup which, 

 in destroying one coloring principle elicits another : for the decolor- 

 ation is uniformly more perfectly effected without heat. With re- 

 gard to the superiority in point of taste, of the syrups filtered by M. 

 Dumont, over those which have been boiled with charcoal, it is 

 much more easily to be comprehended, it being an incontestable fact, 

 that animal charcoal imparts to syrups with which it is heated, a dis- 

 agreeable flavor ; — a flavor which increases with the proportion of 

 charcoal. 



On the other hand, M. D. removes from the charcoal a large pro- 

 portion of the soluble matters by means of the water with which he 

 moistens it. He operates without heat, which is is another reason 

 why his syrups should not acquire any bad flavor. If for perfect 



