1 50 Dh Priestley’s Experiments , &c. 
In the proportion of about io to 9 ; fo that nitrous air does not 
contain quite fo much phlogiil'on as an equal bulk of inflam- 
mable air, as I had before thought to be the cafe. 
In this Paper it will be obferved, that I make the diminu- 
tion of common air by nitrous air to be confiderably lefs than 
I have ufu ally done before. This has been the confequence of 
giving the two kinds of air a little agitation at the inftant of 
mixing, which will generally make the diminution lefs by 
two tenths of a meafure. But I have found, that when thefe 
mixtures of air, with and without agitation, have been kept 
home time, they approach to an equality of bulk. 
At the fame time I have obferved, what I think not a little 
extraordinary, that agitation prevents the greateft diminution 
of dephlogifticated and nitrous air. I have found it to be 2.5 
without agitation, and 6. with it. 
The lefs diminution of the mixture of nitrous and common 
air Is probably owing to the prefence of fo much phlogifticated 
air, which impedes the meeting of the nitrous air with the 
dephlogifticated air in the mixture ; becaufe I find the fame to 
be the cafe when I mix the fame proportion of inflammable 
air with dephlogifticated air; and when dephlogifticated air is 
agitated with nitrous air, the water may impede their union, as 
the phlogifticated air did before. 
There is, therefore, no fource of the nitrous acid which I 
find on the decompofition of dephlogifticated and inflammable 
air, befides the union of thofe two kinds of air, which there- 
fore -do not make mere water , as the antiphlogiftians fuppofe* 
