26 
ON ALCOHOLIC TINCTURES. 
To determine the quantity of alcohol necessary, our aim 
must be to macerate with different quantities of alcohol, 
then to collect the whole of the tincture, and submit it to 
evaporation ; or for the purpose of ascertaining the weight 
of the diminished matters. My first intention was to em. 
ploy expression to extract the tincture, but I was soon con- 
vinced that that method was insufficient ; the same opera- 
tion repeated several times with the same proportions of the 
solvent and the substance, gave me results that differed too 
greatly. In fact, it is impossible so to regulate the pressure 
that it may be the same in all instances; in that case, there 
remains in the residuum a larger or smaller quantity of the 
tincture, and consequently of the principles ; which have, 
nevertheless, been dissolved by the alcohol. 
The following is the process on which I decided, a pro- 
cess which was pointed out, however, in the programme of 
the prize proposed by the Soecite de Pharmacie, and 
which is certainly the best means of arriving at correct con- 
clusions. 
A determinate quantity of the substance was macerated 
for a fitting time in a given proportion of alcohol ; the mace- 
ration being completed, the whole was thrown upon the 
filter, the amount of the filtered tincture was carefully 
weighed, and then evaporated in a sand-bath ; then the ex- 
tract obtained was dried in a stove heated to from 15S° to 
174° until it no longer lost weight. The weight of this ex- 
tract deduced from that of the evaporated tincture, gave me 
the weight of the alcohol contained in that portion of the 
tincture: simple proportion, then, was sufficient to ascertain 
the total weight of the extract which the whole of the 
tincture would have produced. 
15 grammes of cinnamon, for instance, were macerated 
with 5 parts, or 75 grammes of alcohol, at 80° ; the weight 
of the tincture that passed through the filter was 27 gr. -OS; 
that of the extract obtained from this quantity of tincture, 
and completely dried, was Ogr. -94. Deducting 0-94 from 
27-08, we obtained 26-14 for the weight of the alcohol con- 
