a new Eudiometer. 133 
t 
ufecl, it will appear very little better than a mixture of equal 
parts of this and phlogifticated air ; and if twice that quantity 
of nitrous air is ufed, it will appear very little better than a 
mixture of three parts of this air with one of phlogifticated. 
Another great advantage of ufing the full quantity of nitrous 
air is, that thereby the error arifing from any difference in its 
purity is very much diminifhed. 
Perfectly phlogifticated air may be conveniently procured by 
putting fome folution of liver of lulphur into a bottle of air 
well flopped, and fhaking it frequently till the air is no longer 
diminifhed, which r unlefs it is fhaken very frequently, will 
take up fome days. Care muff he taken, however, to 
loofen the ffopper now and then, fo as to let in air to fupply 
the place *of the diminifhed air. In order to know when the 
air is as much diminifhed as it can be, the beft way is, when 
the air is luppofed to be nearly phlogifticated, to place the bottle 
with its mouth under water, ffill keeping it Hopped, and to 
lool'en the ffopper now and then, while under water, fo as to 
let in water to fupply the place of the diminifhed air, by 
which means the alteration of weight of the bottle fhews whe- 
ther the air is diminifhed or not. If the folution of liver of 
fulphur is made by boiling together fixed alkali, lime, and 
flowers of fulphur, which is the moff convenient way of pro- 
curing it,, the air phlogifficated by it will be perfectly free from 
fixed air : whether it will be fo if the liver of fulphur is made 
without lime, I; am not lure. 
A ffill more convenient way, however, of procuring phlo- 
gifficated air is by a mixture of iron filings and fulphur; and* 
as far as I can perceive, the air procured this way is as com- 
pletely phlogifficated as that prepared by liver of fulphur. 
Where 
