No. 414.] NORMAL RESPIRATION. 469 
hold them together in definite form. When the atoms are 
rearranged more compactly in simpler forms in space, their 
bonds or affinities are more completely satisfied, they unite 
more perfectly, oxidation takes place in the rearrangement, 
and energy is accordingly liberated and made available for other 
purposes. Energy is stored in the starch or oil or sugar 
molecule; the kinetic energy (solar or other) employed in the 
construction of the molecule remains in it as potential energy, 
holding the atoms together. The destruction of the molecule 
results in the liberation of so much kinetic energy as was 
employed in constructing it from the simple compounds worked 
upon. i 
The complete oxidation or combustion of a gram of dextrose 
(sugar), resulting in the formation of carbon-dioxide and water, 
as represented by this reaction, 
C6H:206 ES 60, = 6 CO, a 6 H20, 
liberates 3939 small or ordinary calories,! or mechanical units 
of energy in the form of heat? For the sake of obtaining these 
figures in more exact terms, for use in future comparisons, we 
may multiply this with the molecular weight of dextrose, thus: 
atomic weight of C — r2 oft, = 92 
oHe s of Hy = 12 
oro = ag OFC = 96 
' CgH 120. = 180 = molecular weight of dextrose. 
3939 calories x 180 = 709020 calories 
= 709.02 Calories 
The heat of combustion or complete oxidation of 1 gram-mole- 
cule, Ze, of 180 grams, of aei isst is then 709.02 great 
calories (C.). 
This reaction, and the production of this amount of heat, 
take place only in the presence of sufficient quantities of free 
oxygen. Molecules more complex than those of carbon-dioxide 
1 A calorie (c.) is the heat sid to raise 1 gram of water 1? C. in tempera- 
ture; a great calorie (C.) is the heat required to raise 1000 gr. (1 Kilo) of water PG: 
Rechenberg, C. von. Ueber die Verbrennungswärme d Ver- 
ully give 
