Mr. Cavenpisn’s- Experiments on Air. 143 
colour, and treated the. fame quantity of it with volatile alkali 
in the fame manuer as before. It immediately caufed an effer- 
veicence, changed the colour to grey, and yielded 52 grains 
of ammoniacal nitre. There is the utmoft reafon to think, 
therefore, that- red precipitate contains no nitrous acid; and 
coniequently that, in procuring dephlogifticated air fromit, no 
acid is converted into air; and it is reafonable to Geen. 
therefore, that no. fuch change is produced in procuring it from 
any other fubftance. 
Tt remains to. confider in what manner thefe acids a& in 
producing dephlogifticated air. The way in which the nitrous 
acid acts; in the production of it from red precipitate, feems to 
be as follows. On: difti illing the mixture of quickfilver and 
{pirit of nitre, the acid comes over, loaded with phlogitton, im 
the form of nitrous vapour, and continues to do fo till the re- 
maining matter acquires its full red colour, by which time all 
the nitrous acid is driven over, but fome of the watery part full 
remains behind, and adheres ftrongly to the quickfilver; fo that 
the red precipitate may be confidered, either as quickfilver de- 
prived. of part of its phlogifton, and united to a certain portion 
of water, or as quickfilver united to dephlogifticated air™; after 
which, on further increafing the heat, the water in it rifés 
deprived of its phlogifton, that is, in the form of dephlogifticated 
* Unlefs we were much better acquainted than we are with the manner in 
which different fubftances are united together in compound bodies, it would be ~ 
ridiculous to fay, that it is the quickfilyer in the red precipitate ace deprived 
of its phlogifton, and not the water, or that it is the water and not the quighlaetce 
all that we can fay is, that red precipitate confifts of quickfilver and water, one 
or both of which are deprived of part of their phlogifton.. In like manner, during 
the preparation of the red precipitate, it is certain that the acid abforbs phlo- 
gifton, either from the quickfilyer or the water; bus we are by no means authorifed 
to fay from which. j 
alr, 
