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pulfion ; or as a Stimulus, by accelerating their Mo- 
tions, fo as to bring the matter fit for Expulfion, of- 
tener to the fecretory Out let ; or both. 
Thefe Affumptions, which, I exped:, will not be 
difputed, are premifed only for the better proof of 
this grand Proportion. 
That a change in the Bulks, Figures, and Motions 
of the component particles of a purging Medicine, 
will change the feat of its Operation, and fit it for 
exertion in larger or lefler Vedels as thofe mechani- 
cal Affedions are intended, or remitted. 
For Illudration hereof, it may be convenient to 
attend the management of common Pradice, in ma- 
king a Purge operate more, or lefs, than it otherwife 
would do 
Subdances which are grofs and heavy, as thofe con- 
fiding chiefly of Saline and earthly Particles, fiich as 
Tartar, Manna, and the like, if they are reduced 
fmaller by Triture* or repeated Solutions, operate more 
gently, but if acuated by Acids, or any management 
which expofeth their Angles more fenfibly to the 
Membranes, they are rougher, and take Place fooner. 
Refinous Medicines, as Scammony, Gamboge, Jallap, 
and mod of vegetable Produdion are more violent, 
and operate fooner, when they are more tenacious, 
and adhefive, as in their Extrads, but gentler, when 
divided by hard brittle Subdances, fuch as fait of 
Tartar, Sugar, &c. 
Medicines which have in their Compofition, Sul- 
phur and Salt, are more or lefs rough, and fpeedy 
an their Operation, in proportion to their greater or 
lefler participation of the Saline Ingredient, and the 
afperity of its Angles 5 of this kind are mod Mine- 
rals, and their Preparations, and it may be fuffici- 
ent to inftance in the management of Antimony, and 
Mercury ; 
