PHARMACY. 
the leaves : these caterpillars inhabit a com- 
mon web, and usually move in large groups 
together ; their colour is a pale greyish 
yellow, with numerous black spots ; each 
caterpillar at the time of its change to chry- 
salis, envelopes itself in a distinct oval web 
with pointed extremities, and many of these 
are stationed close to each other, hanging 
in a perpendicular' direction from the inter- 
nal roof of the general inclosing web : the 
chrysalis is blackish, and the moth appears 
in tile month of September. To this divi- 
sion also belong the moths, emphatically so 
called, or cloth moths. Of these the prin- 
cipal is the P. vestiauella, which, in its 
caterpillar state, is very destructive to 
woollen cloths, the substance of which it 
devours, forming for itself a tubular case 
with open extremities, and generally ap- 
proaching to the colour of the cloth on 
which it is nourished. This mischievous 
species changes into a chrysalis in April, 
and the moth, which is universally known, 
appears chiefly in May and June. 
In the last division, called Alucitae, is 
one of the most elegant of the insect tribe, 
though not distinguished either by large size 
or lively colours. It is a small moth, of a 
snowy whiteness, and, at first view, catches 
the attention of the observer by the very 
remarkable aspect of its wings, which are 
divided into the most beautiful distinct 
plumes, two in each upiter, and three in 
each under wing, and formed on a plan 
resembling that of the long wing feathers 
of birds, viz. with a strong middle rib or 
shaft, and innumerable lateral fibres. This 
moth, which is the P. pentadactyle of 
Linnaeus, appears chiefly in the month of 
August. Its caterpillar, which is yellow- 
ish green, speckled with black, feeding on 
nettles, and changing into a blackish chry- 
salis enveloped in a white web. 
PHARMACY. This is a very important 
branch of therapeutic science, which in 
tlie article on Materia Medica we have 
observed, embraces the three divisions of 
medicinal materials, the preparation of those 
materials, and the diseases in which they are 
employed. Pharmacy includes the second 
of these divisions; and is, hence, the doc- 
trine of preserving, arranging, compound- 
ing, and intermixing the different articles of 
the Materia Medica, so that as simple sub- 
stances we may obtain their virtues in the 
most active or most convenient form, and, 
in a state of combination, redouble or vary 
their powers according to the intention we 
have in view. In prosecuting this object, 
a multiplicity of operations are necessary, 
some' of them mechanical, some chemical, 
which constitute the means by which the re- 
sult is to be attained ; -and under this natu- 
ral division, the means and the end, phar- 
maceutical operations, and pharmaceutical 
preparations, we shall consider the subject 
before us. 
PART I. 
PHARMACEUTICAL OPERATIONS. 
Under this head we shall comprise the 
mode of collecting and preserving medicinal 
simples ; the mechanical instruments em- 
ployed, and the changes they introduce ; 
chemical instruments and apparatus, their 
use, application, and power. 
Collection and Preservation of Simples, 
Each of the kingdoms of nature furnishes 
articles employed in medicine in their natu- 
ral state, or when prepared by pharmacy ; 
and in collecting these our first attention 
should be to make choice of sound and 
perfect substances ; to throw off whatever is 
injured or decayed, and to separate them 
from all adventitious matters. As a general 
rule they must be defended from the effects 
of moisture, great heat, cold, and freely ex- 
posed to the air. Yet when their activity 
and virtue depend on volatile principles, in- 
stead of being freely exposed to the air, 
they must be confined, as much as possible, 
from its Contact. 
The vegetable kingdom affords us the 
most numerous articles ; these should rather 
be obtained from countries in which they 
grow naturally, than countries in which 
they merely grow by transplantation ; and 
those which grow wild, in dry soils, and ex- 
posed situations, fully open to the air and 
the sun, are for the most part to be pre- 
ferred to plants that are cultivated, or that 
grow in moist, low, shady, and confined si- 
tuations. Annual roots should be collected 
before they shoot forth their stalks or 
flowers ; biennial roots in the harvest of 
their first year, or the spring-time of their 
second ; perennial roots either in the spring 
time before the sap has begun to mount, or 
in harvest after it has returned. Worm- 
eaten or decayed roots, except in a few 
cases of resinous plants, are to be rejected ; 
the rest are to be cleaned immediately with 
a brush of cold water ; immersing them in 
the water as short a time as possible, and 
cutting off the radicles and fibres when not 
essential. Roots which consist chiefly of 
