( 225 ; 
abovefaid Method, to extricate the Air out of their 
Cavities. If they do this, I am confident they will 
meet wi h fome Calculi (as I have done) exceeding 
AlabTfter “and^ 6 S °v ° f burnt Earthen Ware 
A aba ter, and approaching very near to that of Brick 
and the fofter Sort of paving Stone. But it is 2 
7 pe6led - th r at the y Should entirely equal the 
Speufick Gravity of Stone, found in the Earth • be 
an!fv ^ ° f f ° l ? le P ° rd0n 0f the Animal Oil 
H .f2n°r t / e / Sa k V Witl , t ! 1C /r fton y Subftance of the 
3 Zm i™" ”' ds ,h ' s r” fek °'>»r 
e’f • ™ entI< ? n , one ot,lcr Obfervation, relating to 
this Subjed ; which, however trivial it may feemyet 
verM e > WaS 5f PrlZ i ng > when 1 accidentally d’ifco- 
rs r > d n : IS n’ t le Subfiance of all Wood fas 
Oak, Fir, &c.) is fpecifically heavier than Water To 
prevent being mifunderftood, I mult obferve, d,aHn 
v °2 and oth £ r Vegetables, there are two Sorts of 
Veilels ; one of which convey the Sap, and the other 
contain only Air, for which Reafon they a vail’d 
Air-Ve/Tels. When Wood floats, or fwims fn Water 
tins Efted is not ovvmg to the Lightnefs of the Sub- 
fiance ot the Wood, but only to its being buoy’d ud 
by the Air contnin’d in the Vetfels before-faid. 7 Fo? 
when the Air is extracted out of thole VelTels, and in- 
ftead thereof the Water has infmuated it felf into them 
the Wood will fink to the Bottom. As is very eafilylhewn 
Typ allChlpS ' or Shavings of Wood, by means of the 
wVrer U fnf a ra? " 10 boilin g> or even in cold 
Water for a fufecient Time. And the fame is found to 
lucceed in the Roots, Stalks,Leaves,andSeeds of as ma- 
ny other Vegetables as I have yet try'd ,• Cork only ex- 
cepted ,• in which laft I had no Reafon to exped it, con- 
1 1 fiderinj 
’g 
