E2185... 
riments will be concordant with the 
refult of his own. 
When I had an air worfe than 
common air to put to the teft, I 
found Dr. Pricftley’s method ex- 
tremely convenient, by adding’ one 
meafure of nitrous air to one of the 
air under examination ;~ but [T al- 
ways took care to fhake the two airs 
together at the moment of their 
- mutual contact, on gpurpofs to a- 
bridge the e expe) | 
The orincper ching to be ss 
ed to in putting air to the nitrous 
teft, either by the original method — 
of the Rev. Dr. Prieftley, or by any 
other, is to perform with the great- 
iki 
eft nicety every circumitance con=~ 
ftantly in the fame manner in the — 
various €Xperiments ; for, # you” 
allow the two airs to ftand longer 
one time than another, -if- you be=. 
N 4 gee 
