Filter and Prepared Charcoal of M. Dumont. 347 



animal charcoal was superior, and employed it to remove the color 

 of wine, vinegar and the residuum of sulphuric ether. We cannot 

 ascertain from his published memoir that he applied it to syrups. It 

 was a year later that M. Charles Derosne introduced it into the sugar 

 refineries and manufactories of beet sugar, thus rendering great ser- 

 vice to these two branches of national industry, and perhaps a greater 

 to the manufacturers of sal ammoniac, who, until that time, had 

 thrown away as useless all the residuum of their distillations. Since 

 that period the consumption of animal charcoal has been continually 

 increasing and its manufacture has become a source of considerable 

 revenue. Its mode of use underwent little change. After pulver- 

 ization and mixture with the syrup to be decolorized, this was boiled 

 and passed through a woolen cloth 5 by these means its full action 

 was thought to have been attained, and we could not have imagined 

 the possibility of the great improvements in the manner of its em- 

 ployment which M. Dumont has recently introduced. 



This manufacturer, reflecting upon the difficulties of the old pro- 

 cess not only in the use of the charcoal, but also in the washing of 

 the residue and upon the foreign taste acquired by the syrup during 

 ebullition, with that agent sought to remedy them all, and has com- 

 pletely succeeded. His discovery comprises the preparation of the 

 charcoal and its employment by means of a filter of his own inven- 

 tion. The preparation of the charcoal is very simple; it consists in 

 reducing it to grains of equal bigness with those of sporting gun 

 powder, and removing the dust; these grains, however, vary in size 

 withe the density of the syrup to be bleached. 



The filter of M. Dumont is a truncated pyramid turned base up- 

 ward, made of wood and lined throughout with tinned copper. At 

 the lower part is a spigot for drawing off the syrup, a little above that 

 an opening communicating with a tube external to the filter, and 

 used for removing the air of the apparatus. The filter is furnished 

 with two diaphragms of different sizes. When a syrup is to be fil- 

 tered, the small diaphragm is to be placed on the bottom of the filter 

 resting upon four feet, elevating it higher than the spigot and open- 

 ing of the air tube. Upon this diaphragm a piece of coarse cloth is 

 to be extended and upon it the charcoal previously moistened with 

 one sixth of its weight of water, is to be placed in such a manner 

 that all parts shall be equally furnished. The level surface receives 

 another coarse cloth and the larger diaphragm upon which the syrup 

 is to be poured. By this arrangement the effusion of the syrup oc- 



