[ 512 ] 
which are Pearls : I dropped one of near a Line 
Diameter into a Glafs, and that Glafs broke in about 
half an Hour. 
Tho’ the Experiment of rubbing with my Finger 
had convinced me, that the Stroke or Shock of a 
falling Body is not always neceflary to break thefe 
Phials, I thought of fcratching with a Flint the Bot- 
tom of the Glafs, and the Glafs immediately broke. 
To allure myfelf whether the Scratch I had made 
was the Occafion of its breaking, I took a Rod 
of Iron whofe End was rounded ; I pulh’d it Ilrongly 
againft the Bottom of the Glafs, and the Glafs flew. I 
then did the fame, and even pufh’d much harder, againft 
the Bottoms of feveral ordinary Glafles, but without 
any Effect: For tho’ thefe Glafles were much thinner 
than the others, yet none of them ftirred. 
If the Glafles in Queftion are every -where extreamly 
thin, they do not break in the Circumftances above- 
mentioned;! have frequently dropped into fuch Glafles 
the fame Sorts of Bodies as had broken the thicker 
ones, but without any Succefs. I have only met 
with one that fplit-.And I am not even fure but that 
the Weight of the Body dropped into it, which was 
a Stone of fome Size, might occafion its breaking. 
All the Phials upon which I have yet made thefe 
Experiments were of white Glafs: I have not had an 
Opportunity of trying thofe made of the green. 
The Author of the Diflertation, published at 'Pa- 
dua upon this Subject, pretends to account for all 
thefe Angular Phenomena by faying: That the Bo- 
dies dropped into thefe Phials caule a Concuflion that 
is ftronger than the Cohefion of the Parts of the Glafs j 
and that consequently, a Rupture of the fame muft 
enfue. 
