cold water. The valves are so arranged that the gas can get from one to
the other. I will set it in action now, and you can see the gas bubbling
up through the water, as it has been doing all night long, and by this
time we shall find that we have this substance dissolved in the water. If
I take a glass and draw off some of the water, I find that it tastes a
little acid to the mouth: it is impregnated with carbonic acid; and if I
now apply a little lime-water to it, that will give us a test of its
presence. This water will make the lime-water turbid and white, which is
proof of the presence of carbonic acid.

Then it is a very weighty gas--it is heavier than the atmosphere. I have
put their respective weights at the lower part of this table, along with,
for comparison, the weights of the other gases we have been examining:--

Pint. Cubic Foot.
Hydrogen, . . . . 3/4 grains. 1/12 ounce.
Oxygen, . . . . 11-9/10 " 1-1/2 "
Nitrogen, . . . . 10-1/10 " 1-1/4 "
Air,. . . . . . 10-7/16 " 1-3/8 "
Carbonic acid, . . 16-1/3 " 1-9/10 "

A pint of it weighs 16-1/3 grains, and a cubic foot weighs 1-9/10 ounce,
almost two ounces. You can see by many experiments that this is a heavy
gas. Suppose I take a glass containing nothing else but air, and from this
vessel containing the carbonic acid I attempt to pour a little of this gas
into that glass; I wonder whether any has gone in or not. I cannot tell by
the appearance, but I can in this way [introducing the taper]. Yes, there
it is, you see; and if I were to examine it by lime-water, I should find
it by that test also. I will take this little bucket, and put it down into
the well of carbonic acid--indeed, we too often have real wells of