wer po ee the force of aggregation . 
yer eli particles are held in union, and by which that : 
ding to separate them, in order to bring them intoa state of | 
combination, is counteracted : and partly from the state of expan _ 
or of fluidity produced by caloric, by which the surfaces between | 
which chemical attraction is exerted are increased, and the minute 
particles of bodies are brought to act upon each other. 
The oOreRATIONS OF PHARMACEUTIC CHEMISTRY are entirely de 
pendent on chemical attraction, or on the action of caloric. They 
are merely particular arrangements of circumstances, by which the — 
exertion of that attraction is promoted, and the. products of the . 
binations or decompositions which take place are obtained. 
There are several preliminary operations, not directly 
bat ed either to favor the exertion of chemical attraction, 
to facilitate the medicinal operation of the substances subjected i <a 
them. ‘They are those operations, by which bodies are reduced to — 
a state of extreme mechanical division. ‘The principal are puLVERt- 
ZATION, or reducing bodies to powder by beating ; TRITURATION, in 
which the same effect is obtained by rubbing; and LEviGaTION, in 
which the powder is reduced to a greater degree of fineness, from 
the rubbing being continued longer, and being facilitated by the ad- 
dition of any fluid which does not act chemically on the 
“Subjected to the operation, These are performed in m 
earthen-ware, or metal. Aathe oe into which the sub 
oe over a seive, Wasnine or BLUTRIATION is an operation in ) 
which the same end is attained. ‘The powder is agitated in a fluid, 
in which it is not soluble; the larger particles are allowed to sub- 
side; the liquor, holding the finer suspended, is poured off; and, ~ 
on its remaining at rest, are deposited. These methods can be ap- 
plied to few of the metals with advantage. ‘They are, therefore, 
mechanically divided, by filing, by beating into fine leaves, or by 
pouring them when. melted into water ; ; an operation termed granu- 
lation, as the metal becomes solid, in the form of small grains. 
These operations do not directly promote chemical action, as they — 
are far from reducing bodies to their minute particles, between whi 
that action is exerted : they are merely employed as prelimary to 
those which are more directly chemical. 1n pharmacy, some of them 
are of utility, besides promoting chemical combination, as there are’ 
several medicines which act with more certainty and power when 
finely levigated, than. when given in a coarse powder. 
Of the cHemicaL operations, the most important are those by 
which that fluidity is obtained, which is in general requisite for the - 
_ exertion of chemical attraction. Sotutron is the principal operation — 
of this kind. It is that process in which a solid body, when immer- 
sed in a fluid, disappears, so that its particles are no longer di: 
able, and upon standing do not subside, the fluid likewise retaining 
its MS usual transparency. It is merely an ‘example of chemical combi- 
n between two bodies, which happen to exist in different for 
d remaining in the fluidstate. The fluid being 
ore active substance, has been Louped the 
