But now for this atmosphere. First of all, let me tell you the weight of
these gases. A pint of nitrogen weighs 10-4/10 grains, or a cubic foot
weighs 1-1/6 ounce. That is the weight of the nitrogen. The oxygen is
heavier: a pint of it weighs 11-9/10 grains, and a cubic foot weighs 1-3/4
ounce. A pint of air weighs about 10-7/10 grains, and a cubic foot 1-1/5
ounce.
[Illustration: Fig. 25.]
You have asked me several times, and I am very glad you have, "How do you
weigh gases?" I will shew you; it is very simple, and easily done. Here is
a balance, and here a copper bottle, made as light as we can consistent
with due strength, turned very nicely in the lathe, and made perfectly
air-tight, with a stop-cock, which we can open and shut, which at present
is open, and therefore allows the bottle to be full of air. I have here a
nicely-adjusted balance, in which I think the bottle, in its present
condition, will be balanced by the weight on the other side. And here is a
pump by which we can force the air into this bottle, and with it we will
force in a certain number of volumes of air, as measured by the pump.
[Twenty measures were pumped in.] We will shut that in and put it in the
balance. See how it sinks: it is much heavier than it was.
Pages:
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106