nitrous Acid and nitrous Air . 3 1 1 
fphere, viz. phlogifticated and dephlogifticated air. That tliis 
is the cafe, there feems little reafon to doubt. Both the com- 
pofition and decompofttion of nitrous acid renders the fuppofi- 
tion probable. For, 
1. Nitrous air and dephlogifticated air by mixture produce 
nitrous acid ; and nitrous acid, by mere heat, is converted into 
a mixture of phlogifticated and dephlogifticated airs. 
2. Nitrous air, by the methods already related, is changed 
into phlogifticated air, and thefe methods feem to confift in 
abftradiing from the nitrous air a quantity of dephlogifticated 
air. 
3. When nitrous acid and nitre are produced in a natural 
way, the procefs is not well underftood ; but the prefence of 
the atmofphere is known to be neceflary. 
4. Mr, Cavendish’s experiment is decifive on this point. 
The union of the two airs in queftion is effedled by means of 
the eledlrical fpark, and nitrous acid is the product. 
In the next place we are to confider, that volatile alkali 
contains phlogifticated air ; for, 
1. Volatile alkali, by mere heat, or by the eledtrical fpark, 
is changed into a mixture of phlogifticated and inflammable 
air; and, 
2. The reftduum of volatile alkaline air, after the calces of 
lead have been revived in it, is phlogifticated air. 
Therefore, when volatile alkali, in the form of fume or air, 
is applied to red-hot manganefe, or calcined green vitriol (fub- 
ftances which are then yielding dephlogifticated air), with 
thefe fails in view, it feems not difficult to conceive, that one 
of the ingredients of the alkali, viz. phlogifticated air, (hould 
combine with dephlogifticated air, and form nitrous acid or 
nitrous air. If nitrous acid be formed, it will indeed in that 
Y y 2 heat, 
