536 
PHARMACEUTICAL MEETING. 
the liquid so as to make it partly a process of maceration, or by greatly in - 
creasing the quantity of liquid used. The difference in the results, however, 
would be less appreciable in proportion as the disintegration of the substances 
was more complete. In operating upon dense and horny substances, such as 
ergot and galls, if they are only coarsely bruised, the liquid will pass between 
and not through the masses, and the masses being of sensible and unequal 
size, the exhaustion will necessarily be very imperfect. In such case, the ac¬ 
tion of the liquid being principally confined to the surfaces of the masses, the 
more these are extended by disintegration of the substance, the more complete 
will the solvent action be, and in this way only can efficient exhaustion in a 
limited time be effected. 
If the substance operated upon be of a more porous nature, such as capsi¬ 
cum, it may be more completely exhausted in the same time, although the 
disintegration be less perfect than in the other cases. The liquid here may be 
made to pass through the masses of the coarsely powdered capsicum, and the 
percolating process, unaided by maceration, may effect the required object. 
Still, even in this case, more liquid will pass between the masses than through 
them, consequently the surfaces of the masses will be exhausted before the in¬ 
terior parts ; and if it be required to effect the exhaustion with the smallest 
possible quantity of liquid, the masses must be reduced to the smallest practi¬ 
cable size, so as to extend the surface action, and by equalizing the packing 
to render the percolation more complete and efficient. 
It will thus be seen that for carrying out the process of percolation in the 
preparation of tinctures modifications in the mode of operating have to be 
made in different cases, and these admit of, and even require, many variations, 
the exact nature of which it is difficult to indicate without a knowledge of 
all the circumstances under which the operation is conducted, and some of 
which it is impossible to describe verbally. The process is therefore one the 
skilful performance of which is acquired only by experience, and it involves 
more than a little experience, knowledge, and judgment. We may thus ac¬ 
count for the fact, that among those who practise the process, there are hardly 
any two who operate in exactly the same way, and every one is wedded to his 
own mode of operating, and to the form of apparatus that he has been ac¬ 
customed to use. 
There can be no doubt as to the efficacy of percolation, when well con¬ 
ducted, in effecting the exhaustion of solid substances, such as are used in 
making tinctures, and of its superiority over the old process of maceration 
when highly concentrated solutions are required. It is applied, and is only 
applicable, for the treatment of solid matter a part only of which is soluble 
in the menstruum used. It would be useless to apply it to matter that is 
wholly soluble; it is useful only where much of the solid matter is insoluble 
and forms a permanent filter-bed. It is an operation in which all that is solu¬ 
ble in the solid matter operated upon may, by skilful and judicious manage¬ 
ment, be dissolved or extracted with the minimum quantity of solvent. 
It may be asked, to what extent and how does percolation differ in result 
from the action of maceration, wffiere similar quantities of liquid and solid 
substances are used? It will be found, upon examination, that the differ¬ 
ence is material. In maceration, the solid substance being added at once 
to the whole of the liquid menstruum, every solid mass is surrounded by a 
separate portion of liquid, part of wffiich is absorbed from every side by 
capillary attraction, and the liquid which thus penetrates the masses remains 
there sensibly quiescent, the same liquid particles continuing in contact with 
the same solid particles, and no change occurring excepting the very slow 
and imperfect change caused by liquid diffusion, and that effected by the occa¬ 
sional mechanical agitation of the ingredients. In percolation, on the other 
