STATES OP MATTER 3 



when heated, expand and occupy more space. See Section 

 15, Expansion Due to Heat. We make use of the expansion 

 of mercury, in the thermometer, to indicate the degree of 

 heat. See Section 16, Temperature and its Measurement. 



References : 



1. 1703 : 127-128. The Molecular Theory. 



2. 1803 : 82-83. Nature of Matter. 



3. 1803:174-176. Nature of Heat. 

 a. 1801 : 253. Nature of Heat. 

 6. 1802:2-4. Matter. 



c. 1804 : 247-248. Nature of Heat. 



d. 1805 : 306-307. Heat and Energy. 



e. 1806:299-300. Theory of Heat. 



/. 1806 : 301. Relation of Heat and Temperature. 



g. 1807:161-162. Theories of Heat. 



h. 1808 : 206. Definition of Heat. 



t. 1809 : 152-154. Nature and Production of Heat. 



Experiments (for the teacher) in 1803 indicate the molec- 

 ular constitution of solids, liquids, and gases. 



3. STATES OF MATTER 



All material exists in at least one of the following states : 

 If the material has a shape which it can maintain, we 

 call it a solid. If its shape is dependent upon the vessel in 

 which it is held, we give the name liquid to it. Finally, if 

 the material is neither solid nor liquid, but exists either in 

 an invisible form or in a colored, vaporous condition, we call 

 t a gas or a vapor. In a given kind of material the only 

 difference between a solid and a liquid is that the liquid has 

 :nore heat in it than the solid, and likewise the gas has more 



