Abbe Fontan a’s Account of Airs 
circumftances muft lofe either a part or the whole of 
that air which it hath abforbed from the atmofphere. 
It may with fome reafon be fufpcdted, that in my 
.experiments of extracting the air from water by the ac- 
tion of fire, the air might be confiderably altered by the 
vapour of the water itfelf. As this difficulty was of fome 
'force, I endeavoured to remove it in the following man- 
ner. 1 introduced into a tube, through water, a quantity 
«of common air of known goodnefs, and I caufed the 
fleam of water boiling in a matrafs, from which the air 
had been previoufly extracted, to pafs through it. The 
heat of the fleam fometimes made the w r ater occupy 
above five times the fpace it did when cold ; yet the air 
fo treated was not at all altered by it, as appeared by the 
left of nitrous air. The event of the experiment, al- 
though repeated various times, was conftantly the fame. 
I muft obferve, laftly, that having once caufed the air 
of boiling water to pafs into receivers filled with, and 
Handing in, quickfilver, I found that the air was better 
than ufual. I have obferved the fame thing when I have 
oaufed the air to go through diftilled water into receivers 
-filled with it : which obfervation, if the event of the ex- 
periment is conftantly the fame, induces me to believe, 
that the air lofes fome of its good properties by going 
through water not very pure; or, which feems to be 
rather 
