C 278 ] 



water within the tube was on a level 

 with -the brim of the jar ; always 

 taking hold of the glafs tube by 

 means of a piece of linen folded 

 five or fix times, and thoroughly 

 imbibed with water, to prevent the 

 warmth of my hand communicating 

 itfelf to the glafs tube. 



Though 1 fliil think that Abbe 

 Fontana's method of examining at- 

 mofpheric air is the molt accurate ; 

 yet, as I had it more in view to trace 

 nature in the operation of vegeta- 

 bles than to examine the degree of 

 falubrity of the common air, I en- 

 deavoured to abridge this trial as 

 much as poilible, on purpofe to fave 

 time. For this reafon, I got at laft. 

 in the habit of making this trial 

 in the time of a minute or two, 

 -and found a furprizing accuracy in 

 the remit. This mode is in fome 



degree 



