348 Filter and Prepared Charcoal of M. Dumont. 



casions no derangement of charcoal and the irregular flow of the 

 liquid is prevented. The syrup, in percolating the beds of charcoal, 

 displaces the water with which that article was moistened and forces 

 it out at the spigot, where it may be received until it is ascertained 

 that its place has been supplied by syrup, which soon flows in an 

 uninterrupted stream, to be kept up by renewed additions upon the 

 filter. If the charcoal be not wetted with water, the syrup will have 

 more difficult)'' in penetrating its substance, it may pass more in one 

 part than another, and the filtration will not proceed regularly. Be- 

 sides, the water acts another part when animal charcoal is employed, 

 that is, in lixivating (in a partial manner at least) that article, which 

 may be recognized by the salt taste which it acquires. 



M. Dumont made a trial of his filter in our presence with a syrup 

 made from raw sugar. The experiment was successful, and we pre- 

 sent you with the product numbered in the order of their flowing ; 

 the syrup No. 1 is almost colorless. No. 2 of a light amber color. 

 No. 3 a shade darker. By mixing these in equal proportions, a 

 syrup equal to that from good clayed sugar was produced. The 

 purity of taste forms an additional recommendation to these syrups, 

 the flavor of raw sugar being entirely removed. We made a com- 

 parative trial of charcoal in the same proportion, by the old process, 

 and upon the same kind of raw sugar, but the product did not ap- 

 proach the beauty of that obtained by M. Dumont's filter, its color 

 was darker than that of No. 3, and in the taste there was still greater 

 difference, from the syrup having acquired a disagreeable flavor by 

 ebullition with the charcoal. For the decoloration of sugar M, 

 Dumont employs twenty five per cent, of charcoal. This will cer- 

 tainly appear to be a large proportion, but we would observe, that 

 after the first operation, the charcoal retains much of its decolorizing 

 property. Syrup equal in quantity to the first may be poured in 

 and will lose three fourths of its original color ; in fact it will be 

 bleached more than if we had treated the same quantity of sugar 

 with twelve per cent, of charcoal in the ordinary way. 



When decoloration ceases M. Dumont's process still offers ad- 

 vantage. By the way, we would observe, that in the experiments 

 performed before us, M. Dumont employed only fifteen per cent, of 

 charcoal. We have no doubt that had he employed twenty five per 

 cent., as he usually does, the product would have equalled a syrup 

 made with fine refined sugar. After the second operation, the char- 

 coal has lost a great part of its decolorizing action, but M. D. has 

 discovered a property which he calls a_pechante, that is to say, a prop- 



