( lOOJ ) 
tlie confideracion of the Royal Society, if it be found, 
that they may prevent us from running into Errors of 
the greateft ccnfequence. 
Exp- 1. 1 have feveral times cut off a fmall pare 
of t\\Q Crajfamefitum, when by its adhefion to the Tides 
of the Porringer it has Teem’d to fwim upon the Sur- 
face of the Seruw, and have put it into another Vef^ 
fel fill’d with S'rum : upon which it has immediately 
funk to the Bottom. 
Exp. II- When the Coagulum has been buoyd up in 
the Serum by the bubbles of Air adhering to its Sur- 
face, I have Teparated a fmall part of it, where thofe 
Bubbles have been thickeft, and put it into a Glafs of 
Serum> in which it has fwom, as before. Then letting 
the Glafs upon the Air-Pump, thofe Bubbles burfi; af«| 
ter one another, as the Receiver was exhaufling, and 
the Air being again let into the Receiver, the lump 
of Cra([amer)tum funk to the bottom of the Glafs. 
Exp. Ill I have often placed a drop of Serum upon 
a clean Glafs before a Microfeope, in which I had 
diflblv’d a very fmall quantity of Blood, and obferv’d, 
that when the Glafs was held in a perpendicular Po- 
fture, the Blood-Globules fubfided to the bottom of 
the Drop ; and inverting the Glafs, the Globules again 
defeended thro’ the Serum to the Bottom. I had the 
^fame fuccefs with a fmall quantity of Serum and 
Blood in a Capillary Tube, And the fame thing has 
been long fince obferv’d by the famous Mr. Leeumn- 
hoek. 
Thefe Experiments undeniably demonflrate, that the 
Cra([amentum, or globular part of the Blood, is fpecifi- 
cally heavier than the Serum; and confequently it is 
by no means probable, that the Blood Globules are 
Veficles fill’d with Air, or any other Fluid lighter than 
Serum. And that they are not fill’d with any fort of 
9 0 ^ 
