t 251 ] 
A is an oblong trough, about eight inches 
deep, kept nearly full of water, and B, B are jars 
{landing in it, about ten inches long, and two and 
a half wide ; fuch as I have generally ufed for 
'eleflrical batteries. 
C, C are flat {tones, funk about an inch, or half 
an inch, under the water, on which veflels of any 
kind may be conveniently placed, during a courfe 
of experiments. 
D, D are pots nearly full of water, in which 
jars or phials, containing any kind of air, to which 
plants or any other fubftances may be expofed, 
and having their mouths immerfed in water ; fo 
that the air in the iniide can have no communication 
with the external air. 
E is a fmall glafs veflel, of a convenient fize for 
putting a moufe into it, in order to try the whole- 
fomenefs of any kind of air that it may contain. 
F is a cylindrical glafs veflel, five inches in length, 
and one in diameter, very proper for trying whe- 
ther any kind of air will admit a candle to burn 
in it. For this purpofe a bit of wax candle, G, 
may be faftened to the end of a wire, H, and 
Turned up in fuch a manner as to be let down into 
The veflel with the flame upwards. The veflel 
fhould be kept carefully covered till the moment 
that the candle is admitted to it. In this manner 
I have frequently extinguilhed a candle above 
twenty times in one of thefe veflels full of air, 
though it is impoflible to dip the candle into it, 
without giving the external air an opportunity of 
mixing with it, more or lefs. 
Kk 2 I is 
