LIXIVIATION OF VEGETABLE AND ANIMAL SUBSTANCES. 227 
The first trials of this process in pharmaceutic preparations 
were made by Count Real who operated in different modes, 
facilitating the passage of the fluid by means of pressure pro- 
duced by a column of water, by mercury, or by an air pump; 
similar instruments have since been proposed by Payen, 
Geiger, Zenneck and Beral. MM. Boullay on the contrary 
are of opinion that the pressure is useless, and that the opera- 
tion succeeds as well when no such means are used. M. Baudri- 
mont, on the other hand, is convinced, that when pressure is 
used, the different strata of fluid are less apt to mix with each 
other. This pressure cannot be indefinitely increased, for the 
powder at last becomes so much compressed as to prevent 
the passage of the fluid through it. I have also found, that 
the slowness with which the liquid percolates is an advantage; 
as it must have time to penetrate the cells of the plant and 
dissolve the substances contained in them. If the rapidity of 
the flow is increased, the powder is not exhausted. 
The above applies to displacements with alcohol as well as 
to those with water; except that the upper part of the cylinder 
should be provided with a cover to prevent the evaporation of 
the alcohol; as the organic tissues do not swell on contact with 
this fluid as they do with water, the process succeeds better; 
even poppy heads may be treated with advantage. It is ad- 
vantageous that the powder should be previously moistened 
with half its weight of the spiritous liquor. Each substance 
also requires to be compressed in a different manner, but as a 
general rule they all require more pressure than when water is 
used, as they swell less, and because, however slow the perco- 
lation may be, there is no fear of fermentation. 
When a powder has been exhausted by means of alcohol, 
it remains impregnated with a portion of this fluid, which 
should be extracted. MM. Boullay propose to accomplish 
this by displacement with water, but I have not found this to 
succeed, and M. Guillermond has shown the fallacy of this 
method by several well conducted experiments; in these he 
found that the alcohol became mixed with the water in pro- 
portions that went on increasing. 
