PHARMACY. 



few only being saved for the breed of the 

 following year. The moth, when hatch- 

 ed, is a very short-lived animal, breeding- 

 soon after its exclusion, and when the fe- 

 males have laid their eggs, they, as well 

 as the males, survive but a very short time. 



As an example of the Geometrse, we 

 may adduce a very elegant moth, often 

 seen towards the middle of summer, in 

 Europe, o.' the elder, and called P. sam- 

 bucaria ; it is moderately large, of a pale 

 sulphur colour, with angular wings, mark- 

 ed by a narrow transverse brown line or 

 streak It proceeds from a green cater- 

 pillar, which, like those of the rest of this 

 section, walks in a peculiar manner, viz. 

 by raising up the body at each progres- 

 sive movement into the form of an arch or 

 loop, the extremilies nearly approaching 

 each other. It changes in May and June 

 into a black chrysalis, out of which in 

 June or July, proceeds the moth. 



The division called Tineee comprehends 

 those moths which are, in general, of a 

 small size, though often of very elegant 

 colours. Of this tribe is the P. padella r 

 it is of a pearly white colour, with very 

 numerous black spots : its caterpillar is 

 gregarious, appearing in great quantities 

 on various sorts of fruit trees in Europe 

 during the decline of summer, and com- 

 mitting great ravages on the leaves : 

 these caterpillars inhabit a common web, 

 and usually move in large groups toge- 

 ther ; tneir colour is a pale greyish yel- 

 low, with numerous black spots ; each 

 caterpillar at the time of its change to 

 chrysalis, envelopes itself in a distinct 

 oval web with pointed extremities, and 

 many of these are stationed close to each 

 other, hanging in a perpendicular direc- 

 tion from the internal roof of the general 

 inclosing web: the chrysalis is blackish, 

 and the moth appears in the month of Sep- 

 tember. To this division also belong the 

 moths, emphatically so called, or cloth 

 moths. Of these the principal is the P. 

 vestianella, 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 extre- 

 mities, and generally approaching to the 

 colour of the cloth on which it is nourish- 

 ed. 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 Alucitre, 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 

 distuict plumes, two in each upper, and 

 three in each under wing, and formed on 

 a plan resembling that of the long wing 

 feathers of birds', viz. with a strong mid- 

 dle rib or shaft, and innumerable lateral 

 fibres. This moth, which is the P. pen- 

 tadactyle of Linnaeus, an European spe- 

 cies, appears chiefly in the month of Au- 

 gust. Its caterpillar, which is yellowish 

 green, speckled with black, feeding on 

 nettles, and changing into a blackish chry- 

 salis enveloped in a white web. 



PHARMACY. This is a very impor- 

 tant branch of therapeutic science, which 

 in the article on MATERIA MEDICA we 

 have observed, embraces the three divi- 

 sions of medicinal materials, the prepara- 

 tion of those materials, and the diseases in 

 which they are employed. Pharmacy in- 

 cludes the second of these divisions ; and 

 is, hence, the doctrine of preserving, ar- 

 ranging, compounding, and intermixing 1 

 the different articles of the Materia Me- 

 dica, so that as simple substances we may 

 obtain their virtues in the most active or 

 most convenient form, and in a state of 

 combination, redouble or vary their pow- 

 ers, according to the intention we have in 

 view. In prosecuting this object, a mul- 

 tiplicity of operations are necessary, some 

 of them mechanical, some chemical, 

 which constitute the means by which the 

 result is to be attained ; and under this 

 natural division, the means and the end, 

 pharmaceutical operations, and pharma- 

 ceutical preparations, we shall consider 

 the subject before us. 



PART I. 



PHARMACEUTICAL OPERATIONS. 



Under this head we shall comprise the 

 mode of collecting and preserving medi- 

 cinal simples; the mechanical instru- 

 ments employed, and the changes they 

 introduce ; chemical instruments and ap- 

 paratus, their use, application and power. 



Collection and Preservation of Simples. 



Each of the kingdoms of nature fur- 

 nishes articles employed in medicine in 

 their natural 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 



