E473. J 
_. The method of Abbé Fontana in 
putting the different fpecies of air 
to the nitrous teft, cut fhort to the 
whole difficulty arifing from the 
inconftancy_ of ftrength in the _ni- 
trous air. By over-faturating the air 
to be examined with nitrous airy ‘it 
imports little what ftrength nitrous 
air has, though even it had loft al- 
moit its w hole power, of ap gps 
common. air. 
In the method adopted by. 
philofophers, by rE % 
certain proportion of nitrous. air 
is added at once to a certain quan- — 
tity of the air under examination, 
the a very uncertain if the 
ro Poe e 
the fame. ‘quality. But in the me- 
thod of Abbé Fontana this article i is 
ef no confequence at’ allss:<* The 
only difference arifi ing from weak 
= “nitrous 
