[ 2 2 + ] 
’ter, about as much as inflammable air is dimi- 
nifhed in the fame circumftances. For this pur- 
pofe I kept for fome months a quart bottle full of 
each of thefe kinds of air ; but as different quanti- 
ties of inflammable air vary very much in this re- 
fpe£t, it is not improbable but that nitrous air may 
vary alfo. 
From one trial that I made, I conclude that ni- 
trous air may be kept in a bladder much better than 
moft other kinds of air. The air to which I refer 
was kept about a fortnight in a bladder, through 
which the peculiar fmell of the nitrous air was 
very fenftble for feveral days. In a day or two the 
bladder became red, and was much contracted in 
Its dimenfions. The air within it had loft very 
little of its peculiar property of diminifhing com- 
mon air. 
I did not endeavour to afcertain the exa£t quan- 
tity of nitrous air produced from given quantities 
of all the metals which yield it ; but the few ob- 
servations which I did make for this purpofe I lhall 
recite in this place : 
dwt. gr. 
6 o of filver yielded 17! ounce meafu res 
5 19 of quickfilver 4I 
1 2 1 of copper 14! 
2 o of brafs 21 
0 20 of iron 16 
1 5 of bifmuth 6 
o 12 of nickel 4 
VII. Of 
