( i77 ) 
77L 
VI. A new K^nd of Hydrometer . made hy Mr, 
Clarke, and communicated to the Society by 
J. T. Defaguliers, L. L. 2). K ^ S. 
T he Hydrometer, byfome called Areometer, 
is an Inftrument commonly made of Glafs, as re- 
prefented by Figure i, conlifting of a 
Stem A B, graduated by fmall Beads of 
Glafs ‘of different Colours, ftuck on the 
Outfide, a larger Ball, B, quite empty 
as well as the Stem, and a fmall Ball, 
C, filled with Quickfilver before the 
End A, was hermetically fealed, in fuch 
Manner as to make the Hydrometer 
fink in Rain Water as deep as the 
Middle of the Stem. Such an Inftru- 
ment does indeed fhew the different 
fpecifick Gravity of all Waters or Wines, 
by finking deeper in the lighter, and 
emerging'more out of the heavier Li- 
quors but as it is difficult to have the 
Stem exaftly of the fame Bignefs all 
the Way, and if it could be had, the 
fame Inftrument would not ferve for 
Wafer and Spirits,' finking quite over Head in Spirits 
when made for Water, and emerging in Water with 
Part of the great Ball our, when made for Spirits. The 
Hydrometer has only been ufed to find whether any 
one Liquor is fpecifically heavier than another-, but 
hot r to. tell how much, which cannot be done with- 
out , a great deal of Trouble, even with a'nice Inftru- 
ment. The Hydroftatical Balance has fupplied the 
Place 
