GREAT AMOUNT OF ANIMAL HEAT. 



By a number of causes, in appearance 

 entirely distinct, we can thus produce one 

 and the same eflect. In combustion and in 

 the production of galvanic electricity, we 

 have a change of condition in material par- 

 ticles ; when heat is produced by the ab- 

 sorption of light or by friction, we have the 

 conversion of one kind of motion into an- 

 other, wnich affects our senses differently. 

 In all such cases we have a something 

 given, which merely takes another form; 

 m all we have a force and its effect. By 

 means of the fire which heats the boiler of a 

 steam engine we can produce every kind 

 of motion, and by certain amount of motion 

 we can produce fire. 



When we rub a piece of sugar briskly on 

 an iron grater, it undergoes, at the surfaces 

 of contact, the same change as if exposed 

 to heat; and two pieces of ice, when rubbed 

 together, melt at the point of contact. 



Let us remember that the most distin- 

 guished authorities in physics consider the 

 phenomena of heat as phenomena of motion, 

 because the very conception of the creation 

 of matter, even though imponderable, is ab- 

 solutely irreconcilable with its production 

 by mechanical causes, such as friction or 

 motion. 



But, admitting all the influence which 

 electric or magnetic disturbances in the ani- 

 mal body can have on the functions of its 

 organs, still the ultimate cause of all these 

 forces is a change of condition in material 

 particles, which may be expressed* by the 

 conversion, within a certain time, of the ele- 

 ments of the food into oxidised products. 

 Such of these elements as do not undergo 

 this process of slow combustion, are given 

 off unburned or incombustible in the exe- 

 crements. 



Now, it is absolutely impossible that a 

 given amount of carbon or hydrogen, what- 

 ever different forms they may assume in the 

 progress of the combustion, can produce 

 more heat than if directly burned into atmos- 

 pheric air or in oxygen gas. 



When we kindle a fire under a steam 

 engine, and employ the power obtained to 

 produce heat by friction, it is impossible 

 that the heat thus obtained can ever be 

 greater than that which was required to 

 heat the boiler ; and if we use the galvanic 

 current to produce heat, the amount of heat 

 obtained is never in any circumstances, 

 greater than we might have by the com- 

 bustion of the zinc which has been dissolved 

 : ji the acid. 



The contraction of muscles produces heat; 

 but the force necessary for the contraction 

 Ins mini Tested itself through the organs of 

 motion, in which it has been excited by 

 chemical changes. The ultimate cause of 

 the heat produced is, therefore, to be found in 

 these chemical changes. 



By dissolving a metal in an acid, we 

 produc^ an electrical current ; this current, 

 if passed through a wire, converts the wire 

 p^ a magnet, by means of which, many 



different effects may be produced. The 

 cause of this phenomena is magnetism ; the 

 cause of the magnetic phenomena is to be 

 found in the electrical current ; and the ulti- 

 mate cause of the electrical current is found 

 to be a chemical change, a chemical action. 



There are various causes by which force 

 or motion may be produced. A bent spring, 

 a current of air, the fall of water, fire ap- 

 plied to a boiler, the solution of a metal in 

 an acid, all these different causes of mo- 

 tion may be made to produce the same 

 effect. But in the animal body we recog- 

 nise as the ultimate cause of all force only 

 one cause, the chemical action which the 

 elements of the food and the oxygen of the 

 air mutually exercises on each other. The 

 only known ultimate cause of vital force, 

 either in animals or in plants, is a chemical 

 process. If this be prevented, the pheno- 

 mena of life do not manifest themselves, or 

 they cease to be recognisable by our senses. 

 If the chemical action be impeded, the vital 

 phenomena must take new forms. 



According to the experiments of Despretz, 

 1 oz. of carbon evolves, during its combus- 

 tion, as much heat as would raise the tem- 

 perature of 105 oz. of water at 32 to 167, 

 that is, by 135 degrees; in all, therefore, 

 105 times 135=14207 degrees of heat. 

 Consequently, the 13*9 oz. of carbon which 

 are daily converted into carbonic acid in the 

 body of an adult, evolve 13-9xl4207= 

 197477-3 degrees of heat. This amount of 

 heat is sufficient to raise the temperature ol 

 1 oz. of water by that number of degrees, 

 or from 32 to 197509-3; or to cause 

 136-81bs. of water at 32 to boil; or to 

 heat 370 Ibs. of water to 98-3 (the tem- 

 perature of the human body;) or to convert 

 into vapour 24 Ibs. of water at 98-3. 



If we now assume that the quantity ot 

 water vaporized through the skin and lungs 

 in 24 hours amounts to 48 oz. (3 Ibs.,) then 

 there will remain, after deducting the neces- 

 sary amount of heafr, 146380-4 degrees of 

 heat, which are dissipated by radiation, by 

 heating the expired air, and in the excre 

 mentitious matters. 



In this calculation, no account has been 

 taken of the heat evolved by the hydrogen 

 of the food, during its conversion into water 

 by oxidation within the body. But if Ave 

 consider that the specific heat of the bones, 

 of fat, and of the organs generally, is far 

 less than that of water, and that conse- 

 quently they require, in order to be heated 

 to 98-3, much less heat than an equal 

 weight of water, no doubt can be enter- 

 tained, that when all the concomitant cir- 

 cumstances are included in the calculation, 

 the heat evolved in the process of combus- 

 tion, to which the food is subjected in the 

 body, is amply sufficient to explain the con- 

 stant temperature of the body, as well as 

 the evaporation from the skin and lungs. 



VI. All experiments hitherto made on the 

 quantity of oxygen which an animal con 

 sumes in a given time, and also the enn^l i 



