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 
passed through a woolen cloth; 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 acquiredeby 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 sy: up oc- 
