Entered according to Act of Congress. A. D, 1897, by A. N. BELL, in the office of the Librarian of Congress, at Washington.

CATALOGUED

AUG 12 1899

E. H. B.

12

THE SANITARIAN.

JULY, 1897.

NUMBER 332.

THERMICS AND THERMO-DYNAMICS OF THE BODY.

BY F. J. B. CORDEIRO, M. D., P. A. SURGEON, U. S. NAVY.

The animal kingdom, in regard to heat, can be divided broadly into two classes--cold-blooded animals and warm-blooded animals. The former conform to the temperature of their suroundings, their vital-chemical reactions taking place with nearly equal facility through a wide range of temperatures. The latter possess a certain definite temperature which they maintain at all times and which may be considered a life function of the species. The difference is entirely one of equlibrium.

All bodies, whether living or dead, must lose or gain heat from the surrounding medium according as their temperatures are higher or lower than that of the medium. In cold-blooded animals this loss of heat is greater than the production, and consequently an equilibrium is not reached until the temperature of the body has nearly coincided with that of its envelope. In warmblooded animals, on the other hand, since life can exist only within certain narrow limits of temperature, the expenditure and gain of heat must at all times be nicely balanced. Under different conditions it will be seen that the members of such an equation may vary widely, though the equality must always be maintained. The body, then, can be considered a thermostat set to a certain vital tempera

ture.

In studying the movement of heat in a body it is essential to know the specific heat, the penetrability and permeability to heat, of its various parts. Such constants have unfortunately (so far as the writer knows), not been determined for living bodies or for most animal tissues. The total quantity of heat in an idividual would be the sum of the specific heats of its parts multiplied by their masses, into the absolute temperature, which we may consider as 310. The average specific heat of the body might be de