ee 
SECTION Xx. 
Experiments tending to inveftigate- 
the mofi accurate and expeditious 
“way of putting common air to the 
tefi, on purpofe to judge of the [a- 
: eat of a RED, : 
the atroduction to the fecond part 
of this work, of the accuracy with 
which this difficult and important 
inveftigation may be made by em- 
ploying the inftruments of Abbe 
Fontana; but as there is much more 
attention and ‘dexterity required to 
judge with the greateft nicety of 
the degree of falubrity of the at- 
- mofpheric air than of any other, 
oo as the other airs-are of much lefs 
en ge = importance 
~ 
