( tooo 
rentiam non Tatis attendiHe videtur Dod^iffimus Jurlfilus] 
a vero multum aberrafle mihi videtur. Si igitur fepo-, 
fid fua, de Vaforum idu, hypothec, & vi preflurae, 
qu^ Natura utitur, pro Principio adhibit^, alia Theo- 
remara de Cordis & Sanguinis motu & viribus, elegan- 
te fu^ demonftrationis methodo, conftruere dignabitur, 
fefe dignum, mihi cerre grarum, nec eruditis inutile 
praeftiterit. Tu, qui Rci Medico principatum tenes, Vir 
Ampliffime, dilfentientium difputationes tua prudentia 
ita moderari digneris, ne IndotHs ludibrio, fed ut Do- 
(Stis emolumento efl'e pofTint. Dabam NorthamptonU 
^3. die Junii 1719. 
III. An account of feme Experime?its relating to the 
Specific k Gravity of Human Hood, <By James 
Juriiij M. D. and F. R. S, 
I T is well known from the Obfervations of Mr< 
Leeujvenhoek and others, that Human Blood confifts 
of red globular Particles, fwimming in a pellucid Lym- 
pha, or Serum. Which two different Subftances, tho* 
of unequal Specifick Gravities, yet fo long as they con- 
tinue to circulate in the Veins and Arteries, are pre- 
vented from feparating by their Motion and Warmth,’ 
But when the Blood comes to ftagnate and cool in a 
Porringer, the globular Particles uniting together by 
their attractive Power, 'and finking by their Weight, 
which is greater than that of the Serum^ form the 
Coagulum, or Craffamentum, at the bottom of the Por- 
ringer, the Serum fwimming above it. 
Ihings always happen in this manner, when the 
Craffamentum is at liberty to fubfide : but it often falls 
out, that, either by its adhefion to the fides of the 
yeflel, or by the bubbles of Air, which the Blood 
. ^ gathers 
) 
