( 7 < ) 
IV. A Letter of Dr, John Quincy, to the late 
learned Mr, Sam. Moreland, F.R. S, concerning 
the Operation of Medicines . 
H A T I had an opportunity fome time fince 
of faying in Convention concerning the Ope- 
ration of Medicines, and particularly of Purges, I 
here beg leave to fend you for a Re-Examination, 
becaufe I Ihall be glad to have my thoughts con- 
firm’d by your Approbation, or be advertis'd of any 
midakes which felf Partiality may lead me into, be- 
fore they are too far drawn into Confequences. 
With regard to this affair I fuppofe, 
i. Thar all thole parts of an animal Body, 
which are vafcular, or through which any Fluid paf- 
feth, from the Inteftines to the minuted: Fibre, are 
the feat of Medicine’s Operation. 
That this whole courfe of Circulation, or Ani- 
mal Motion is naturally didinguidied into three dif- 
ferent Stages, by the different capacities of the Veffels 
and motions of their Contents, each having its proper 
Out-let, and that thefe are the feat of the three Con- 
co&ions, fo often mentioned by Phyfical Writers ; the 
firft in the Stomach and Bowels, having the Anus 
for its Emun&ory ; the fecond, all within the Blood’s 
motion, fo far as it retains its Colour, having the 
Kidneys ; and the third, all beyond that Circuit, ha- 
ving the Skin for an excretory Organ. 
3. That every Medicine which caufeth Evacuation 
is a Purge. 
4. That every Purge operates as a Didolvent, by 
fufing the Juices, and increafing the quantity fit for Ex- 
L 
pulfion 5 
