nitrous Acid and nitrous Air # 3 05 
minutes, yet it fcarcely appeared worth while to trouble the 
Royal Society with a detail of the experiments ; and I only 
prefume to do it now', becaufe the conjedlures which I then 
formed have been fufficiently verified by future experiments. 
The conjedlures were as follow : 
10. Almoft immediately upon feeing the volatile alkali 
produced by means of nitrous acid and metals, I conceived 
the poflibility of inverting the order of the procefs, and of 
producing nitrous acid or nitrous air by the decompofition of 
volatile alkali. I knew of no experiments wherein this had 
been done, or any thing like it ; yet as volatile alkali was 
beyond all difpute produced in the method juft defcribed, and 
as the iron turnings and infide of the gumbarrel were left after 
the operation in a ftate of calcination, it feemed not unna- 
tural to fuppofe, that by forcing volatile alkali through the 
red-hot calces of fome of the metals, nitrous acid or 
nitrous air might be produced. Some of my friends, to 
whom I mentioned the idea, confidered it as a random con- 
jecture. However, I made a memorandum of it as a thing 
that deferved to be tried, though in fad I negleCled for near 
two years actually to make the trial. It was fome time in the 
month of March, 1788, that the calx of manganefe on ac- 
count of its very great infufibility, and its yielding abundance 
of dephlogifticated air, occurred to me as a very proper fub- 
ftance for the purpofe. I immediately crammed a gun-barrel 
full of powdered manganefe; and to one end of the tube I 
applied a fmall retort, containing the cauftic volatile alkali* 
As foon as the manganefe was heated red-hot, a lighted can- 
dle was placed under the retort, and the vapour of the boiling 
volatile alkali forced through the gun-barrel. Symptoms of 
nitrous fumes and of nitrous air foon difeovered themfelves, 
and 
