STUDIES OF MATTER AND LIFE. 
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fact, tlieir powers. A gas — or common air, which is a mixture 
of gases — resists pressure and exerts pressure, because its 
particles are in vigorous, rapid, and ceaseless motion. Sub- 
stances that are translucent, or transcalorescent, are so composed 
that ether waves go through them as water goes through a 
sieve. Bodies that do not allow light or heat to pass in this 
way, have their molecules set in motion by the impulse of 
the ether waves, and thus new forms of force are generated. 
Tyndall’s beautiful experiments on the powers of various 
substances to absorb heat and stop its radiation offer most 
instructive instances of the power exerted by small quantities 
of matter. Taking the absorption of one atmosphere of common 
air to be unity (1 ), it was found that this power was augmented 
thirty-fold when the same quantity of air was permeated by 
a little vapour of patchouli ; lavender vapour raised it to 60 
times, camomiles to 87, cassia to 109, and aniseed to 372. 
Upon these results Tyndall remarks “ that the number of atoms 
in the tube (experimented with) must be regarded as almost 
infinite in comparison with those of the odours. ... it would 
be idle to speculate on the quantities of matter implicated in 
these results. Probably they would have to be multiplied by 
millions to bring them up to the pressure of ordinary air. 
Thus — 
The sweet South 
That breathes upon a bank of violets, 
Stealing and giving odour, 
owes its sweetness to an agent which, though almost infinitely 
attenuated, may be more potent as an intercepter of terrestrial 
radiation than the entire atmosphere from bank to sky.” * 
Wherever we find power exhibited, matter is in motion, and 
if the quantity of matter is infinitely small, and yet the power 
great, it is because the motion is infinitely quick. The waves 
of chemical force streaming from the sun are very short, and 
the quantity of matter acting in each oscillation, and tapping 
at the molecules on which it acts is inconceivably minute, but 
the taps are as inconceivably numerous and rapid. They are 
also rhythmical, and we know how the stone walls of a large 
building may be set in vibrating motion when an organ tone 
of the right pitch impels air waves to go on tap, tap, tapping 
till the whole fabric shakes. 
We learn from these and similar facts that the wave forces 
-can give great powers to infinitesimally small portions of matter, 
and that, as we are not able to place any limit that we can 
comprehend to the possible velocities of atoms and molecules, 
* T} T ndall, ‘‘Heat as a Mode of Motion.” 
