Pharmacy. 
distilled by boiling them in water in the 
Common manner. 
Plants differ so much, according to the 
Soil and season of which they are the pro- 
duce, and likewise according to their own 
ages, that it is impossible to fix the quantity 
of water to be drawn from a certain weight 
of them to any invariable standard. The 
distillation may always be continued as 
long as the liquor runs well flavoured off the 
subject, but no longer. 
In the distillation of essential oils, the 
Water, as was observed in the foregoing 
section, imbibes alwaj's a part of the oil. 
The distilled liquors here treated of, are 
no other than water thus impregnated with 
the essential oil of the subject; whatever 
smell, taste, or virtue,- is communicated to 
the water, or obtained in the form of watery 
liquor, being found in a concentrated state 
in the oil. 
All those vegetables, therefore, which 
contain an essential oil, will give over some 
virtue to water by distillation : but the de- 
gree of the impregnation of the water, or 
the quantity of water which the plant is 
capable of saturating with its virtue, are 
by no means in proportion to the quantity 
of its oil. The oil saturates only the water 
that comes over at the same time with it 
if there be more oil than is sufficient for 
this saturation, the surplus separates, and 
concretes in its proper form, not miscible 
witli the water that arises afterwards. Some 
edorifeious flowers, whose oil is in so small 
quantity that scarcely any visible mark, of 
it appears, unless fifty or an hundred pounds 
or more are distilled at once, give never- 
theless as strong an impregnation to water 
as those plants which abound most with 
oil. 
Many have been of opinion, that distilled 
waters may be more and more impregnated 
With the virtues of the subject, and their 
strength increased to any assigned degree, 
by cohobation, tliat is, by re-distilling them 
repeatedly from fresh parcels of the plant ; 
experience, however, shews the contrary. 
A water, skilfully drawn in the first distilla- 
tion, proves, on every repeated one, not 
stronger, but more disagreeable. Aqueous 
liquors are not capable of imbibing above 
a certain quantity of the volatile oil of vege- 
tables ; and this they may be made to take 
np by one, as well as by any number of 
distillations : the oft^er tlie process is re- 
peated, the ungrateful impression which 
they generally receive from- the fee, even 
at the first time, becomes greater and 
greater. 
Those plants which do not yield at first 
waters sufficiently strong, are not proper 
subjects for this process. 
The mixture of water and oil which 
comes over, may either be separated imme* 
diately, by means of a separatory, or after 
it lias been put into large narrow-necked 
bottles, and placed in a cool place, that the 
portion of oil which is not dissolved in the 
water, may rise to the top, or sink to the 
bottom, according to its specific gravity. 
It is then to be separated, either by a se- 
paratory, or by means of a small glass sy- 
ringe ; or by means of a filter of paper ; or, 
lastly, by means of a Woollen thread, one 
end of which is immersed in the oil, and the 
other lower end in a phial •- the oil will thus 
pass over into the phial by capillary atti ac- 
tier., and the thread is to be squeezed dry,- 
Most distilled waters, wlien first pre- 
pared, have a somewhat unpleasant smell, 
which, however, they gradually lose : it is 
therefore advisable to keep them for some 
days after their preparation in vessels but 
slightly covered ; and not to cork them up 
until they lose that smell. 
That the waters may keep the better, 
about one-twentieth part of their weight of 
proof spirit may be added to' each after 
they are distilled. I have been informed 
by a respectable apothecary, that if tlie 
simple distilled waters be rectified by dis- , 
tilling them a second time, they will keep 
for several years without the addition of 
any spirit, which always gives an unplea- 
sant flavour, and is often objectionable for 
other reasons. 
Distilled waters are employed chiefly as 
grateful diluents, as suitable vehicles foC 
medicines of greater efficacy, or for render- 
ing disgustful ones more acceptable to the 
palate and stomach : few are depended on^ 
with any intention of consequence by them- 
selves. 
To the chapter on simple distilled wa- 
, tecs, the London college have annexed the 
following remarks, 
“We have ordered most of the Waters to 
be distilled from the dried herbs, because 
fresh ai-e not ready at all times of the year. 
Whenever the fresh are used, the weights 
are to be increased. But, whether, the 
fre.sh or dried herbs be employed, the ope- 
rator may vary the weight according to the 
season in which they have been produced 
and collected,” 
1 . 
