( ) 
Secretions are formed in the Blood before they arrive 
at their fecerning Glands : But becaufe the Particles of 
tile Blood returning by the Veins and attra6Hng one 
. another, are formed into Globules too big for any Se- 
cretion, he Blows how thefe Globules are broken and 
, -divided in the Lungs by the force of Refpiration : And 
from Experiments, and the Do8:rine oi Staticks, he 
calculates the prdfure of the Air upon the Lungs to be 
equal to 'the weight of loo Pound ; and becaufe the 
did'erence between the greatefl: and lead: Gravity of the 
Air is To of the greatelf, he from thence fhows how 
Alfmatick People are very fenlible of this difference, 
elpecially when they breathe thicker ; for if they per- 
form their Expiration in half the ufual time, it will 
make this diBerence equal to 40 Pound weight, which 
is almoff equal to half the Preffure of the Air in ordinary 
Breathing. * • . 
He Blows, in the nextr place, how from the great Ve- 
locity of the Blood, the friction on the Coats of the 
Veffels, the Impetus of the Particles on one another, 
and their Elafficity, there muB: needs arife near the 
Heart a Brong inteltine Motion in the Blood, on which 
depends its heat ; and by confequence near the Heart, 
where the Motion is greatefl: , the union of the Parti- 
cles will- be in a great meafure hinder’d ; and therefore 
the Particles that unite firfl:, are fuch as have the ffrong- 
efl: attraftive force, and fuch as have the leafl:, are the 
lafl: in uniting. The Particles endowed with the 
iirongefl: attradive Powders, are, by his 2d Prop, the 
moll Solid and Spherical Corpufcle^^ and their quantity 
of ContaH: being the leafl:, the Secretion they compole 
muff be the moil Fluid : Such is the Liquor in the Pr- 
ricardium. ■ 
Upon the fame Principle, he giVes the Reafon of the 
ficuation of the Kidneys fo near the Heart, that the Salts 
that are in Urine, being Brongly attraftive, and uniting 
dofely 
