PIONEER INVESTIGATIONS \) 
Quite different is the explanation of these phenomena given by Lavoisier 
and de la Place." As a result of their experiments on a guinea-pig they 
conclude : 
Ainsi, Ton peut regarder la chaleur qui se degage dans le changement de l'air pur en 
air fixe, par la respiration, comme la cause principale de la conservation de la chaleur 
animale, et si d'autres causes concourent a l'entretenir, leur effet est peu considerable. 
La respiration est done une combustion, a la verite fort lente, mais d'ailleurs par- 
faitement semblable a celle du charbon; elle se fait dans l'interieur des poumons, sans 
degager de lumiere sensible, parce que la matiere du feu, devenue libre, est aussitot absorbee 
par l'humidite' de ces organes: la chaleur developpee dans cette combustion se commu- 
nique au sang qui traverse les poumons, et de-la se repand dans tout le systeme animale. 
Ainsi, l'air que nous respirons, sert a deux objets egalement n^cessaires a notre conserva- 
tion; il enleve au sang la base de l'air fixe, dont la surabondance seroit tres-nuisible; et la 
chaleur que cette combinaison depose dans les poumons, repare la perte continuelle de 
chaleur que nous eprouvons de la part de 1' atmosphere et des corps environnans. 
... la conservation de la chaleur animale est due, au moins en grande partie, a la 
chaleur que produit la combinaison de l'air pur respire par les animaux, avec la base de 
l'air fixe que le sang lui fournit. 
While the researches of Crawford and of Lavoisier and de la Place showed 
that the animal body was capable of giving off heat and that muscular work 
increased the oxidative processes, the fact that external muscular work could 
be converted into heat was first brilliantly demonstrated by Count Rumford. 
This investigator made experiments in which the work of horses was employed 
to turn a steel cannon-borer pressed against the bottom of a hollow metal 
cylinder immersed in water. He calculated that the heat produced by friction 
in such an apparatus was equal to that continuously produced in the combus- 
tion of 9 wax candles, each three-fourths of an inch in diameter. At the end 
of about two hours the water actually boiled. He says: 
As the machinery used in this experiment could easily be carried around by the force 
of one horse (though to render the work fighter two horses were actually employed in 
doing it) these computations show further how large a quantity of heat might be produced 
by proper mechanical contrivance merely by the strength of a horse, without either fire, 
light, combustion, or chemical decomposition; and in a case of necessity the heat thus pro- 
duced might be used in cooking victuals. But no circumstances can be imagined in which 
this method of procuring heat would not be disadvantageous; for more heat might be 
obtained by using the fodder necessary for the support of a horse as fuel. 6 
Beginning with the experiments of Lavoisier, a new impulse was added 
to the search for the source of animal heat. Lavoisier's personal belief that 
the lungs are the seat of combustion was contested by Lagrange, 6 who argued 
that if the quantity of heat developed in the body in the course of a day was 
actually produced in the lungs it would necessitate such a high temperature 
as to cause destruction. The discovery that respiration also took place 
through the skin d independent of the lungs further complicated the matter. 
The discussion thus started waged continuously until in 1837 Magnus 6 con- 
cluded that the combustion did not take place exclusively in the lungs, but 
in the capillaries in general throughout the entire body — a conclusion that 
has been accepted from that time. 
a Lavoisier and de la Place, Memoire sur la chaleur. Memoires de l'Acadfimie Royale des Sciences, 1780, p. 
405, et seq. Printed in Paris, 1784. 
t> Rumford's Essays, London, 1798, 2, p. 488. 
e Lagrange cited by Hassenfratz. Ann. de Chim., 1791, 9, p. 266. 
a Spallanzani, M6moires sur la respiration, Geneva, 1803. 
« Magnus, Ueber die ein Blute enthaltenen Gaze; Sauerstoff, Stickstoff und Kohlensaure, Poggendorff's Ann. 
der Phys. u. Chem., Leipsic, 1837, 40, p. 583; 1845, 66, p. 177. 
