PHARMACY. 
ly to the evaporation. 2. When water is 
totally incapable of dissolving the substance 
to be extracted; and, 3. When the sub- 
stance extracted can bear the heat of boil- 
ing alcohol without being evaporated, but 
would be dissipated by that of boiling water; 
that is, when it requires a heat greater than 
176°, and less than 212°, for its vaporiza- 
tion. 
In the last case, the alcohol must be per- 
fectly free from water, because the heat 
necessary to evaporate it at the end of the 
process would frustrate the whole opera- 
tion. Hence, also, the subject itself ought 
always to be dry : those substances which 
lose their virtue by drying, lose it equally 
on being submitted to this treatment with 
the purest alcohol. 
In this way the alcoholic extract of some 
aromatic substances, as cinnamon, lavender, 
rosemary, retain a considerable degree of 
their fine flavour. In the second case, the 
alcohol need not be so very strong, because 
it is still capable of dissolving resinous sub- 
stances, although diluted with a consider- 
able proportion of water. In the first case, 
the alcohol may be still much weaker; or 
rafher, the addition of a small proportion 
of alcohol to water will be sufficient to re- 
tard or prevent the decomposition of the 
decoction. 
The alcohol employed in all these cases 
should be perfectly free from any unpleasant 
flavour, lest it be communicated to the 
extract. 
The inspissation should be performed 
from the beginning, in the gentle heat of a 
water-bath. We need not suffer the al- 
cohol to evaporate in the air : the greatest 
part of it may be recovered by collecting 
the vapour in common distilling vessels. 
If the distilled spirit be found to have 
brought over any flavour from the subject, 
it may be advantageously reserved for the 
same purposes again. 
When diluted alcohol is employed, the 
distillation should only be continued as 
long as alcohol comes over ; and the evapo- 
ration should be finished in wide open ves- 
sels. 
Pure resins are prepared, by adding to 
spiritous tinctures of resinous vegetables a 
large quantity of water. The resin, inca- 
pable of remaining dissolved in the watery 
liquor, separates and falls to the bottom, 
leaving in the menstruum such other prin- 
ciples of the plant as the spirit might have 
extracted at first along with it. But this 
is only practised for the purpose of ana- 
lysis. 
Extracts made with Water only. 
Extractum gentianas luteae, Edin. ex- 
tract of gentian. Having cut and bruised 
any quantity of gentian, pour upon it eight 
times its quantity of water. Boil to the 
consumption of one half of the liquor, and 
strain it by strong expression. Evaporate 
the decoction immediately to the consist- 
ence of thick honey, in a bath of water 
saturated with muriate of soda. 
In the same manner are prepared ex- 
tracts 
Of the roots of liquorice, extractum gly- 
cyrrhiza? glabrae. 
Of the roots of black hellebore, extrac- 
tmn hellebori nigri. 
Of the leaves of rae, extractum rutaj gra- 
veoleptis. 
Of the leaves of senna, extractum cassire 
sennae. 
Of the flowers of camomile, extractum 
anthemidis nobilis (chamaemeli). 
Of the heads of white poppy, extractum 
papaveris albi. 
Of logwood, extractum haematoxyli Cam- 
pechensis. 
Extract of broom tops, extractum cacu- 
minis genistae. 
Extract of camomile, extractum chamae- 
meli. 
Extract of savin, extractum sabinte. 
The other extracts of this division are, 
Extractum cinchonae, Lond. extract of 
Peruvian bark. 
Extractum haematoxyli, Lond. extract of 
logwood. 
Extractum opii, Dubl. extract of opium. 
Extractum sennae. Loud, extract of senna. 
Extracts made with Alcohol and Water. 
Extractum cinchonae officinalis, Edin. e,x- 
tractum cinchonae cum resina, Lond. resin 
of bark. 
Extractum radicis convolvuli jalapae, Edin. 
extractum jalapii, Lond. resin of jalap. 
Extractum cascarillae, Lond. resin of cas- 
carilla. 
Extractum colocynthidis compositum, 
compound extract of colocyntli. 
Class XX. Pulveris. Powders. 
This form is proper for such materials 
only as are capable of being sufficiently- 
dried to become pulverisable without the 
