( loop ) 
tioned in his Experiment; and confequenriy a fmall 
error in the height of the Liquor would make a confi- 
derable alteration in the Specifick Gravity. 
Since therefore the Specifick Gravity of Human Blood 
is lo^q, and that of its Seruw 1030, it is plain, that 
Blood is heavier than Serum by about one part in 43. 
From which it manifedly follows, that the Globular 
part of the Blood is fpscifically heavier than the Serum, 
fince the Globular part being feparated from the Blood 
leaves the remainder, or the Serum) fpecifically lighter 
than the intire Mafs. 
But in order to determine the exadt Specifick Gra- 
vity of the Blood Globules, it is firft necefiary to know 
the Proportion, which the whole quantity of the Craf. 
famentum contained in Blood bears to the Serum. To 
this end Mr. Bo^le has given us two feveral Obferva- 
tions of the weights of the Crajfamentum and Serum, af- 
ter they have feparated one from another in the Por- 
ringer. But befides the difficulty of making this Ex- 
periment with any tolerable exadfnefs, it is to be con- 
fider’d, that there is a great deal of Serum contain’d in 
the interftices of the Globules, that compofe the Crajfa- 
mentum. 
This difficulty however is in fome meafure anfwer’d 
by two other Experiments, which Mr. Boyle made for 
this purpofe, after the following manner. He put a 
quantity of the Craij'amerrtum, already feparated from 
the Seram, into an Alembick, and diftill’d off the re- 
maining Serum to drynefs, but without drawing off the 
Oil, or Volatile Salt ; after which he weigh’d the di- 
ftill’d Liquor, and the dry Mafs left behind. 
By comparing, thefe Experiments with the two for- 
mer, it will be found that the entire weight of Serum 
contain’d in Blood is nearly If of the whole, and con- 
fequently 
