(2158) 
them they did not appear to me to have any (harp Angles, 
and amongft the reft there was one of an Oval figure and 
as big a Man's Fift, and when it was thrown into the 
Water in my prefence, I faw it float with the half of its 
Body above the Superfices of the Water 5 from whence I 
concluded, that by its long driving in the Water the 
Angles of fuch a Stone were fo worn off, that inftead of 
having (harp and uneven points, they were grown to be 
blunt and fmooth. 
And it may alfo fo happen, that from the Rocks, whe- 
ther they be in the Sea or upon the Shoars thereof, . fuch 
a foft Matter as thefe Stones feem to be compofed of is 
torn or feparated by ftormy Winds. 
When I laid the fame Stone upon the Fire, 1 could per- 
ceive a fmoaky Matter evaporating from it. 
This laft mentioned Experiment induced me ta take 
fome of the little pieces of the Stone, in order to keep to- 
gether, as much as it was poflible, the Matter which was 
exhaled from them 5 and accordingly I did perceive that 
the firft Matter which was driven off was as bright a Va- 
pour as one (hould fee, but the next, which was forced 
out by a yet ftronger Fire, was nothing near fo bright, 
and was moreover laden with an unfpeakable number of 
exceeding fmall Particles 5 which, by reafon of their 
weight, funk to the bottom, after which that Vapour 
became clear: There was alfo drawn off from the fame 
Stone a little Matter, which I look upon to be Sulphur. 
I have indeed before now heard fay, that the Spungas 
which are found in the Sea did grow upon the Rocks, 
which however I could hardly conceive, believing that the 
folid Rocks could not produce fuch a fort of Matter 5 
but when I came to be informed that there are whole 
Rocks in the Sea compofed of Pumice-ftone, 'tis eafy to 
imagine that they may produce fuch a Matter as we call 
%)unge. 
I 
