CXXII
APPENDIX.
Α. Equivalence of heat and mechanical work.
§ 304. As often as mechanical work is performed in order
to produce heat, one and the same quantity of work is neces
sary for producing one thermal unit (to raise one pound of water
through one degree Centigrade § 139). The experiments of
Ioule and Hirn have proved, that be the work friction or the
force of a river or compression or magnetism, for obtaining one
thermal unit 424 units of work are neccessary. (An unit of work
we call the force required for raising 1 kilogramme through one
metre.)
§ 305. As often as by heat mechanical work is done, part
of the heat is absorbed; one thermal unit is spent by 424 units
of work. 424 Metre-kilogramme work we call the equivalent of
work for one thermal unit. 1/424 or 0.002358 is called the equiva
lent of heat for a dynamical unit.
B. Conservation of Energy
or the incorruptibility of matter.
§ 306. The preceding sections have shown, that mechani
cal work is never lost, but only changed into heat and on the other
hand that heat is changed into mechanical work. But in the
same manner we have also come to understand, how mechani
cal work may be used to produce magnetism or electricity or
that heat may cause electricity, on the other hand electricity may
be the cause of heat, light, mechanical work and chemical pro
cesses and that chemical combinations call forth heat, light,
electricity etc. Now, if all the physical forces we know of may
be exchanged for each other, the conclusion seems to be justified,
