PHARMACY. 
adapted for medical purposes ; and by the 
increase of their surface their action is pro- 
moted, botli as medical and chemical agents. 
It is performed by cutting, bruising, grind- 
ing, grating, rasping, filing, pulverization, 
trituration, and granulation, by means of 
machinery or of proper instruments. 
Pulverization is the first of these opera- 
tions that is commonly employed in the 
apothecary’s shop. It is performed by 
means of pestles and mortars. The bottom 
of the mortars should be concave ; and their 
sides should neither be so inclined as not to 
allow the substances operated on to fall to 
the bottom between each stroke of the 
pestle, nor so perpendicular as to collect it 
too much together, and to retard the opera- 
tion. The materials of which the pestles 
and mortars are formed should resist both 
the mechanical and chemical action of the 
substances for which they are used. Wood, 
iron, marble, siliceous stones, porcelain, and 
glass, are all employed : but copper, and 
metals containing copper, are to be avoided. 
They should be provided with covers, to 
prevent the finest and lightest parts from 
escaping, and to defend the operator from 
the effects of disagreeable or noxious sub- 
stances. But these ends are more com- 
pletely attained by tying a piece of pliable 
leather round the pestle and round the 
mouth of the mortar. It must be closely 
applied, and at the same time so large, as 
to permit the free motion of the pestle. In 
some instances it will be even nece.ssary for 
the operator to cover his mouth and nostrils 
with a wet cloth, and to stand with his back 
to a current of air, that the very acrid par- 
ticles which arise may be carried from him. 
The addition of a little water or spirit of 
wine, or of a few almonds, to very light and 
dry substances, will prevent theii” flying off. 
But almonds are apt to induce rancidity, 
and powders are always injured by the diy- 
jng which is necessaiy when they have been 
moistened. Water must never be added to 
substances which absorb it, or are rendered 
cohesive by it. 
All vegetable substances must be previ- 
ously dried. Resins and gummy resins, 
which become soft in summer, must be 
powdered in very cold weather, and must 
be beaten gently, or they will be converted 
into a paste instead of being powdered. 
Wood, roots, barks, horn, bone, ivory, &c. 
must be previously cut, split, chipped, or 
rasped. Fibrous woods and roots should be 
finely shaved after their bark is removed, for 
otherwise their powders will be full of hair- 
like filaments, which can scarcely be sepa- 
rated. Some substances will even require 
to be moistened with mucilageof tragacaiith, 
or of starch, and then dried before they can 
be powdered. Camphor may be conveni- 
ently powdered by the addition of a little 
spirit of wine, or almond oil. The en)nlsive 
seeds cannot be reduced to powder unless 
some dry powder be added to them. To 
aromatic oily substances sugar is the best 
addition. All impurities and inert parts 
having been previously separated, the ope- 
ration must be continued and repeated up- 
on vegetable substances till no residunm is 
left. The powders obtained at different 
times must then be intimately mixed toge- 
ther, so as to bring the whole to a state of 
perfect uniformity. 
Very hard stony substances must be re- 
peatedly heated to a red heat, and then 
suddenly quenched in cold water, until they 
become sutficiently friable. Some metals 
may be powdered hot in a heated iron mor- 
tar, or may be rendered brittle by alloying 
them with a little mercury. 
Trituration is intended for the still more 
minute division of bodies. It is performed 
in flat mortars of glass, agate, or other-liard 
materials, by giving a rotatory motion to 
the pestle ; or on a levigating stone, which 
is generally of porphyry, by means of a 
muller of the same substance. On large 
quantities it is performed by rollers of hard 
stone, turning horizontally upon each other, 
or by one vertical roller turniust on a flat 
stone. 
The substances subjected to this opera- 
tion are generally previously powdered or 
ground. 
JLevigation differs from trituration only 
in the addition of water or spirit of wine to 
the powder operated upon, so as to form 
the whole mass into a kind of paste, which 
is rubbed until it be of sufficient smoothness 
or fineness. Earths and some metallic sub- 
stances are levigated. 
Granulation is employed for the mecha- 
nical division of some metals. It is per- 
formed, either by stirring the melted metal 
with an iron rod until it cools, or by pouring 
it into water, and stirring it continually as 
before, or by pouring it into a covered box, 
previously well rubbed with chalk, and 
shaking it until the metal cools, when the 
rolling motion will be converted into a 
rattling one. The adhering chalk is then 
to be washed away. 
Mechanical Separation is obtained by sifti 
