Increased transmission implies diminished absorption; and
accordingly, the respective absorption of ether vapor and liquid ether,
when the lime light was used, instead of being 66.7 and 67.2 per cent.,
were found to be
Vapor....................33.3 per cent.
Liquid...................33.3 "
no difference whatever being observed between the two states of
aggregation. The same was found true of hydride of amyl.
This constancy and continuity of the action exerted on the waves of heat
when the state of aggregation is changed, I have called "the thermal
continuity of liquids and vapors." It is, I think, the strongest
illustration hitherto adduced of the conservation of molecular action.
Thus, by new methods of search, we reach a result which was long ago
enunciated on other grounds. Water is well known to be one of the most
opaque of liquids to the waves of obscure heat. But if the relation of
liquids to their vapors be that here shadowed forth, if in both cases
the molecule asserts itself to be the dominant factor, then the
dispersion of the water of our seas and rivers, as invisible aqueous
vapor in our atmosphere, does not annul the action of the molecules on
solar and terrestrial heat. Both are profoundly modified by this
constituent; but as aqueous vapor is transparent, which, as before
explained, means pervious to the luminous rays, and as the emission from
the sun abounds in such rays, while from the earth's emission they are
wholly absent, the vapor screen offers a far greater hinderance to the
outflow of heat from the earth toward space than to the inflow from the
sun toward the earth.
Pages:
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120