HAL PHILOSOPHY. 



I) 



1 1 2. T. Can you give me a more definite 

 .:' it ? 



/'. Ills a very subtile, elastic fluid, which 



its effects, and th 



tions it produces. It penetrates all bodies, 



more or less, and exists in all bodies, but 



cannot be wholly separated from them. It 



in zfree, and in a latent or concealed 



state. Its particles are supposed mutually 



to repel each other, and its rays are 



c ipable of reflexion and polarization, and 



irangiblc. 



113. T. How do you know that heat 



P. Because I can detect its presence in 

 various ways ; for example, it' I rub a but- 

 ton upon my coat, it will soon become so 

 hot that it will ignite a lucifer-match ; and 

 if I hammer the end of a piece of iron wire- 

 it will become hot enough to ignite phos- 

 phorus or gunpou 



114. 7*. What is the reason that heat 

 is developed by friction, and hammering 

 the iron ? 



Because the atoms of which the 

 materials are composed are compressed, 

 and the heat which was latent or concealed 

 i* forced out, and made sensible, or 



7*. What effect does heat produce 

 upon bodies ? 



iifies attraction, and regulates 

 their solidity or density. 



)iunicated? 

 'y conduction and radiation. 



117. 7*.- What do you mean by con- 



Vhrn the heat passes from atom to 

 atom slowly along a body, it is con 

 thus, i: ! .< end of a small i 



a can- 



die, the heat will soon be conducted or 

 ' 



i' ba --hut Mill the heat is 



reason of this is, that 



metals are the best conductors ; then fluids, 

 and last of all, u 



US. 7'. What do you mean by the 

 radiation of heat? 



P. It simply means, th:tt the heat is 

 given ofF in rays or lines. 



11!'. T. Can you give me some other 

 peculiarities and properties relating to 



/'. Yes ; but they will be more suited 

 to the subjects of Chemistry and Pneu- 

 matics. 



120. T. Although you have explained 

 to me that heat is the great agent of repul- 

 sion, yet you have nol given me a single 

 example to prove that. 



ily done: [Experiment 

 20] Take two feathers, rub a glass tube 

 about 1J inch in diameter pretty briskly 

 with a silk handkerchief, and then touch 

 both feathers, one after the other; the lir^t 

 effect produced will be attraction. Now 

 i em near to each other, and the 

 result will be repulsion : they will separate 

 themselves. 



i'.AL QUESTIONS ON LESSON IX. 

 1. What name ha* been given to the 

 property which causes the atom* of bodies 

 to separate, or recede from each other 1 



<>*thispri !> all bodies? 



.use of its acting .' 

 Vhat is cal><: 

 >ve that it exists, 

 hat are the sources of heat? 

 .it illict docs it produce upon 



hr.it cominunic 



i action 

 ami r.ulia'.ion of heat? 



t xamples of the repulsion of 

 bodies. 



[Tli* pupil should gire other example! than 



m ihe 



o lmiUr bodies, like wood, to 

 prove that heat is latent, *c. ftc.J 



LESSON X. 



rm LATIOX, &c. WE have learned that heat possesses remarkable properties ; 



and although it is unequally distributed over the sui t has a con- 



y to preserve , .-,> in all fixations. When we know mote 



