CHEMICAL SCIEXCE. 213 



and glowing, by only striking it continuously with a hammer ; here 

 mechanical power is converted into heat. If we produce so much 

 heat as is necessary for raising the temperature of one pound of water 

 by one degree, then we must apply an amount of mechanical work 

 equal to raising one pound of water 1389 feet, and lose it for gaining 

 again that heat. By these considerations it appears to be proved 

 that heat cannot be ponderable matter, but a motive power, because 

 it is converted into motion, or into mechanical power, and can be 

 produced either by motion or mechanical power. Now, in the steam- 

 engine, we find the heat is the origin of the motive-power, but the 

 heat is produced by burning fuel, and therefore the origin of the mo- 

 tive-power is to be found in the fuel, that is, in the chemical forces of 

 the fuel, and in the oxygen with which the fuel combines. 



The Sun's Heat. According to the hypothesis of La Place, the 

 universe was formed by a chaos of nebulous matter, spread out 

 through infinite space, this nebulous matter becoming afterwards 

 conglomerated and aggregated to solid masses. Great quantities of 

 this nebulous matter" possibly from a great distance, fall together, 

 and thus their attraction, or the energy of their attraction, was de- 

 stroyed, and thus heat must have been produced heat so great that 

 it surpasses all our ideas and all the limits of our imagination. If we 

 calculate this quantity of heat, and suppose that the sun contained 

 the whole of it, and if we suppose that the sun had the same specific 

 heat as water, it would be heated to twenty-eight millions of degrees, 

 that is, to a temperature surpassing all temperatures we know on 

 earth. However, this temperature could not exist at any time in the 

 sun, because the heat which was produced by the aggregation of the 

 masses must also be spent partially by radiation into space. Never- 

 theless, the sun is at present hotter than any heated body here on 

 earth, as is shown by the latest experiments of Kirchhoff and Bunsen 

 on the spectrum of the sun, by which it is proved that in his atmos- 

 phere iron and other metals are contained as vapor, -which cannot 

 be changed into vapors by any amount of heat on the earth. 



Conversion of Heat into Mechanical Force in the Body. Dr. 

 Edward Smith has instituted researches on the amount of air taken 

 into, and of carbonic acid given out, by the lungs of a man while 

 doing work on the treadmill, and he finds that a most astonishing in- 

 crease of respiration takes place during such work. His experiments 

 showed that, by going in the treadmill at such a rate that if he went 

 up-hill at the same rate he would have risen during one hour 1712 

 feet, he exhaled five times as much carbonic acid as in the quiet 

 state, and ten times as much as in sleeping. The treadmill is the 

 best method of getting the greatest amount of work from a human 

 body. If we go up the declivity of a hill we raise the weight of our 

 own body ; in the treadmill the same work is done, only the mill goes 

 always down, and the man on the mill remains in his place. The 

 human body, if it be in a reposing state, but not sleeping, consumes 

 so much oxygen, and burns so much carbon and hydrogen, that dur- 

 ing one hour as much heat is produced as would raise the tempera- 

 ture of a weight of water equal to the weight of the body 2| degrees 

 Fah., the mechanical equivalent of which is rising 1712 feet; so that 

 the amount of mechanical work done in a treadmill is equivalent to 



