308 Mr. Milner on the Vrodudllon of 
12. Thefe obfervations are made principally for the fake of 
thofe who may wifh to repeat thefe experiments. The main 
point to be eftablhhed, is the adtual formation of nitrous air 
by this method. And this truth I confider as proved beyond 
all controverly ; for by continuing the procefs patiently, and 
applying repeatedly frefh portions of ftrong volatile alkali to 
the fame manganefe, kept Conftantly hot in the gun-barrel, I 
have often collected large jars of air, which was proved to be 
highly nitrous by mixture with atmofpherical or with dephlo- 
giiticated air. 
13. It is not eafy to fay, whether in this procefs dephlo- 
gifticated nitrous air, or even nitrous acid itfelf, be not fome- 
times immediately formed by the aftion of the volatile alkali 
on the manganefe. Traces of the former, in fome inftances, 
feem to difcover themfelves; but I do not fpeak decidedly on 
th is head. As to the latter, it is very certain, that fumes of 
the nitrous acid often circulate in the jars that receive the air. 
But poflibly thefe fumes may arife from the decompofition of 
4 nitrous air, by means of the fuperfluous dephlogifticated air 
of the manganefe. 
14. The fteam of boiling water was applied to red hot man- 
ganefe in a fimilar way ; not the leaf!: nitrous appearance; but 
the fixed and dephlogifticated airs were generated much more 
plentifully than when the manganefe was urged by mere heat. 
When thefe airs had been collected in large quantities, the 
volatile alkali was applied as before to the refiduum of the 
xnanganefe, and nitrous air foon appeared. 
15. As manganefe is known to produce a very extraordinary 
change upon fpirit of fait in a moderate heat, it feemed not 
improbable, that a ftill greater change might take place by 
working in this method. Accordingly I forced the vapour of 
3 boiling 
