2 inches in the one case, and of 6.6 inches in the other.
In passing through the liquid layer, a beam of heat encounters the same
number of molecules as in passing through the vapor layer: and our
problem is to decide, by experiment, whether, in both cases, the
molecule is not the dominant factor, or whether its power is augmented,
diminished, or otherwise overridden by the state of aggregation.
[Footnote 1: The millimeter is 1-25th of an inch.]
Using the sources of heat before mentioned, and employing diathermanous
lenses, or silvered minors, to render the rays from those sources
parallel, the absorption of radiant heat was determined, first for the
liquid layer, and then for its equivalent vaporous layer. As before, a
representative experiment or two will suffice for illustration. When the
substance was sulphuric ether, and the source of radiant heat an
incandescent platinum spiral, the absorption by the column of vapor was
found to be 66.7 per cent. of the total beam. The absorption of the
equivalent liquid layer was next determined, and found to be 67.2 per
cent. Liquid and vapor, therefore, differed from each only 0.5 per
cent.; in other words, they were practically identical in their action.
The radiation from the lime light has a greater power of penetration
through transparent substances than that from the spiral. In the
emission from both of these sources we have a mixture of obscure and
luminous rays; but the ratio of the latter to the former, in the lime
light is greater than in the spiral; and, as the very meaning of
transparency is perviousness to the luminous rays, the emission in which
these rays are predominant must pass most freely through transparent
substances.
Pages:
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119