SCIENCE AND THE PROPERTIES OF MATTER 3 



adhesion, are common to all forms of matter and may be 

 considered as general characteristics. Others, such as brit- 

 tleness and ductility, which are found only in certain kinds 

 of matter, are called specific characteristics. 



4. Cohesion, Adhesion, and Inertia. The particles of 

 matter in solids and liquids are held together by a force 

 called cohesion. This cohesive force is stronger in some bodies 

 than in others. Sometimes the word tenacity is used instead 

 of cohesion. We may speak of a substance as possessing 

 great tenacity or great cohesion; such a substance is said 

 to be tenacious. Correctly speaking, tenacity is the measure 

 of cohesion. 



The property of a substance which enables it to stick or 

 cling to another substance is called adhesion. Glue, for 

 instance, is held to wood by adhesion. 



Inertia is the tendency of a body to retain its condition 

 of rest or of motion. The inertia of a hammer prevents 

 it from moving itself. A lathe tends to run after the 

 power is shut off. 



5. Elasticity and Ductility. When a carpenter bends 

 the blade of his saw and releases it, the saw blade tends 

 to return to its original position. This property is called 

 elasticity. 



A substance is said to be ductile when it can readily be 

 extended or drawn out. Copper, because it possesses a 

 high degree of ductility, can be drawn out into wire. 



6. Brittleness and Toughness. When a substance breaks 

 easily under strain it is said to be brittle. Glass furnishes a 

 good example of a particularly brittle substance. 



