AMPERE’S THEORY OF HEAT AND LIGHT. 
27S 
of the temperature of the regions of space, 
which the earth successively traverses, be- 
cause he considers it very improbable, that 
the temperature of space is every where the 
same. The mean temperature of space may 
be admitted to differ little from zero, in place 
of being, as has been generally calculated 
below the temperature of the coldest regions 
of the globe. The variations in the tempera- 
ture of space may, however, be very consi- 
derable, and they ought to produce corres- 
ponding variations in that of the earth, which 
will extend to depths dependant on their 
extent and degree. ‘‘If we suppose, for 
example, a block of stone to be carried from 
the equator to our latitudes, its cooling will 
have commenced at the surface and extended 
into the interior, and if it has not reached 
the whole mass because the period has been 
insufficient ; this body when it has arrived 
in our climate will present the phenomenon 
of a temperature increasing from the surface. 
The earth is in the condition of this block of 
stone ; it is a body which proceeds from a 
region whose temperature was superior to 
that of its present situation ; or, if we wish, 
it is a thermometer, moveable in space, 
which has not time, inconsequence of its 
great dimensions and its degree of conducti- 
bility, to take in through its whole mass the 
temperature of the different regions which 
it trasverses. At present, the temperature 
of the globe increases below its surface. 
The contrary has already, and will again 
take place. At other periods, besides at 
epochs separated by numerous ages, this 
temperature ought to be, and will be, by 
consequence, much higher or much lower 
than it is now, which prevents the earth from 
being alvrays habitable by the human species, 
and has, perhaps, contributed to the succes- 
sive revolutions of which its external layer 
has preserved the traces.”* 
2. THEORY OF HEAT AND LIGHT.— 
Ampere, in stating his views in reference to 
a theory of heat, sets out with defining 
ticles, molecules, and atoms which he consi- 
ders to enter into the constitution of matter. 
A pat^icle is an infinitely small portion of a 
body, and of the same nature with it, so that 
a particle of a solid body is solid, that of a 
liquid body liquid, and that of a gas aeriform. 
The particles are composed of molecules kept 
at a distance ; 1. By what remains at this 
distance, of the attractive and repulsive 
forces peculiar to the atoms ; 2. By the re- 
pulsion which the vibratory motion of the in- 
terposed ether establishes between them : 
and 3. By the attraction directly proportional 
to the masses, and inversely as the 
square of the distance. Molecules consist of 
a collection of atoms kept at a distance by 
attractive and repulsive forces peculiar to 
each atom. Atoms are material points from 
which these attractive and repulsive forces 
emanate. 
* Bibliotheque Universelle, June, 1835, 
Ann. de Chimie, lix. 71. 
From this definition, it follows, he consi- 
ders that a molecule is essentially solid, 
whether the body to which it belongs be 
solid, liquid, or gaseous ; that the molecules 
are polyhedrons, of which these atoms, or at 
least a certain number of these atoms occupy 
the summits, and it is these polyhedrons that 
are termed primitive forms by crystallogra- 
phers. The particles alone can be separated 
by mechanical means. The force which re- 
sults from the vibrations of the atoms may 
separate the compound into simpler mole- 
cules. Chemical action can alone separate 
the latter. Thus, in detonnating a mixture 
of 1 volume of oxygen and 2 volumes of 
hydrogen, by which 2 vols. of vapour of water 
are formed, each molecule of oxygen is 
divided into two, and the atoms of each of 
these halves unite with the atoms of a mole- 
cule of hydrogen to form a molecule of water. 
Proceeding upon these premises. Ampere 
distinguishes the vibrations of molecules 
from those of atoms. In the first, the mole- 
cules vibrate together, approaching and 
retreating alternately the one from the other, 
and whether they vibrate in this manner or 
remain at rest, the atoms of each molecule 
vibrate and, in fact, always do vibrate by ap- 
proaching and retreating the one from the 
other alternately, without ceasing to belong 
to the same molecule. The latter, he terms 
atomic vibrations. To the vibration of the 
molecules, and to their propagation in the 
surrounding media he attributes all the 
phenomena of sound ; to the vibrations of 
the atoms he ascribes all those of heat and 
light.* 
3. OPTICAL PROPERTIES OF CHAR- 
COAL. — If a portion of well burned fir char- 
coal be placed upon a layer of heated coal on a 
wind furnace, and all openings be closed, so 
that no air can penetrate below the coal, the 
combustion will be carried entirely by the 
decomposition of the carbonic acid. After 
the fire has subsided. Degen found that the 
portion of Icoal had wholly or in part dissolv- 
ed into amass of fibres, which did not adhere 
strongly to each other. When examined 
under the microscope they were found to be 
round tubes ; they are more or less translu- 
cent, and their colour by transmitted light 
is brownish yellow. These tubes have round 
apertures on their sides, whose margins are 
thicker than the rest of the sides ; some of 
them when of a large size, however, have no 
edges of any considerable diameter. When 
heated to whiteness in platinum foil before 
the blowpipe, these tubes lost their trans- 
lucency and became very brittle. The dia- 
meter of these tubes was from about*00049 
inch to 0000908 inch. I here is remarkable 
appearance observed when the miscros- 
cope is directed through one of the aper- 
tures upon a distant {entfernten) object. 
This object appears double. One of the 
figures stands upright about. 0004 behind 
the opening ; it is, at least so distinct, that 
* Ann. de Chim. et de Phy». Iviii. 
