24 
ON ALCOHOLIC TINCTURES. 
tain, according to these authors, the quantity of soluble mat- 
ter in a given weight that any substance can furnish. 
l]hese points being ascertained, we must have recourse 
to a fresh operation to determine the relative quantity of 
the two vehicles necessary to hold in solution all the solu- 
ble principles. These operations consist in preparing satu- 
rated tinctures, by macerating the substances you wish to 
operate upon in the smallest possible quantity of alcohol at 
36° B., filtering and evaporating a determinate weight of 
the tincture, to ascertain the quantity of matter held in so- 
lution, to repeat the same operation with distilled water ; 
then to discover the quantity of alcohol necessary to dis- 
solve a certain portion of the extract obtained by the alco- 
hol, and to repeat the operation with water and the extract 
obtained by that solvent. It will be sufficient then to mul- 
tiply by the quantity of the extract furnished by the sub- 
stance, the quantity of each liquid necessary to dissolve an 
aliquot part of the extract, to obtain the proportions of alco- 
hol and water, the mixture of which would be proper for 
the preparation of the tincture. 
This process, ingenious as it is, is nevertheless not exact, 
for it rests upon a principle, the proof of which is far from 
being proved — a principle, which, in the generality of cases, 
is even false. 
In fact, it is not correct to say that if we macerate sepa- 
rately in alcohol and water a substance containing resinous 
oily matters, and with extractive and gummy substances, 
we dissolve, by means of alcohol, all the matter soluble in 
that liquid that the substance contains, and that it is the 
same in the case of water. For, in order that that might be 
true, it would be necessary that these matters, of a nature 
so distinct from each other, should exist in the vegetable in 
a state of complete separation. 
Is it not, on the contrary, more reasonable to imagine that 
these substances are in a nearly complete state of combina- 
tion, and, that, being thus combined, they are not separated 
by the separate action of each solvent ? It is only in this 
