[ 97 ] 
It was fomewhat furpriiing to find, that after this 
period of immerfion the cork had not, as might have 
been expected, loft any force of buoyancy ; but on 
the contrary, it had adtually gained two grains, and 
was found to fupport 918 grains of lead: which 
muft be attributed, it may be prefumed, to an ex- 
panlion of the air contained in the cork, acquired 
from its immerfion in the frefli water. 
To be further informed how cork would be affcd:ed 
by a continued immerfion, the fame float, after 
weighing, was again immerfed in the fame water, 
for the fpace of 48 hours longer. And now the water 
was found to have penetrated its recefl'es and cavities, 
in fo much that its buoyancy had decreafed 1 1 grains, 
and it then only lupported 905 grains. This decreafe 
may poflibly be attributed to a greater imbibition in 
the cork, and a greater penetration given to the wa.- 
ter, by its having been now 96 hours in a chamber, 
with a'fire in it, by which it might be warmed. This 
float A being taken out of the water, wiped, and 
laid in a dry place for 24 hours, weighed 21 1 grains, 
having gained by abforption 21 grains of additional 
weight. 
Experiment IV. 
The float, in this ftate, having been 24 hours out 
of the frefti water, was now put into fait water- 
brought from the North Foreland, in which it was 
found to fupport the weight of 954 grains, of a 
leaden medallion, having the power of buoying up 
38 grains more in the fea water, than it did in the 
river water, with which it was nearly faturated at the 
time of its immerfion in the fea water. 
VoL. LV. O 
After 
