20 INTRODUCTION. 



QUESTIONS. 



1. What is matter, and what is mass? 



2. Mention the principal fundamental properties of matter. 



3. Mention the three states of aggregation. 



4. Describe the characteristic properties of matter in the solid, 

 liquid, and gaseous state. 



5. What is cohesion ? 



(1 Give a definition of a crystallized substance. 



7. Under what circumstances will matter crystallize ? 



8. State the difference between amorphous, polymorphous, and iso- 

 morphous substances. 



9. What is meant by elasticity of gases ? 



10. State the Law of Mariotte. 



2. DIVISIBILITY. 



Mechanical comminution. All matter admits of being sub- 

 divided into smaller particles, and this property is called divisi- 

 bility. The processes by which we accomplish the comminution 

 of a solid substance may be of a mechanical nature, such as 

 cutting, crushing, grinding, but besides these modes of sub- 

 division we have another agent by which matter may be divided 

 into smaller particles, and this agent is heat. 



Action of heat on matter. Let us take a piece of ice and con- 

 vert it, by means of mortar and pestle, into a very fine powder. 

 When the smallest particle of this finely powdered ice is placed 

 under the microscope and heat applied we will observe that it 

 turns liquid, thus proving that it was capable of further sub- 

 division, that it consisted of smaller particles, which have now 

 by the action of heat become movable. By further applying 

 heat to the liquid particle of water we may convert it into a gas 

 or vapor, which will escape into the air, or which we may 

 collect into an empty flask. The flask will be filled completely 

 by this water-gas (or steam) obtained by vaporizing that minute 

 particle of ice-dust. This fact demonstrates that mechanical 

 comminution does not carry us beyond a certain degree of sub- 

 division of matter. That is to say, the smallest fragment of the 

 finest powder still consists of a very large number of much 

 smaller particles. To the smallest particles which compose 

 matter, the name molecules has been given. 



