SCIENCE OF COMMON THINGS. 177 



Form of bodies dependent on heat. Heat expands all matter. 



of matter is thus made to occupy a larger space ; the 

 diminution of heat has an opposite effect. 



The expansion of solids by heat is 

 clearly shown by the following experi- 

 ment, Fig. 40 : m represents a ring of 

 metal, through which, at the ordinary 

 temperature, a small iron or copper 

 ball, a, will pass freely, this ball being a 

 little less than the diameter of the ring. 

 If this ball be now heated by the flame 

 of an alcohol lamp, it will become so 

 far expanded by heat as no longer to 

 pass through the ring. 



116J3 Is Hie form of bodies depend- 

 ent on heat ? 



It is. 



1163 Sow is this shown ? 



By the increase of heat, solids are converted into 

 liquids, and liquids are dissipated into vapor ; by its 

 decrease, vapors are condensed into liquids, and these 

 become solid. 



1164 If matter ceased to be influenced by heat, what would be the effect? 



All liquids, vapors, and doubtless even gases, would 

 become permanently solid, and all motion on the sur- 

 face of the earth would be arrested. 



1165 What are the three most apparent effects of heat, so far as relates 

 to the form and dimensions of bodies ? 



Expansion, liquefaction, and vaporisation. 



1166 Does heat expand air f 



Yes ; if a bladder (partially filled with air) be tied 

 up at the neck, and laid before the fire, the air will 

 expand till the bladder bursts. 



1167 Why will the air swell if the bladder be Md before the fire f 



Because the heat of the fire will drive the particles 

 of air apart from each other, and cause them to occupy 

 more room than they did before. 



116S Does heat expand all matter ? 



Yes ; every thing (that man is acquainted with) is 

 expanded by heat. 



1169 How can we prove that solids expand with heat f 



