4 APPLIED SCIENCE 



Toughness, on the other hand, is that property which 

 enables a substance to resist cutting and to bear strain 

 without breaking. 



7. Malleability and Compressibility. A malleable sub- 

 stance is one which can be rolled or hammered into sheets 

 without breaking or cracking. Gold and silver both possess 

 a high degree of malleability. 



When the particles of a substance can be forced to occupy 

 a small space, that substance possesses the property of com- 

 pressibility. 



8. Porosity, Durability, and Infusibility. Every body 

 of matter is composed of very fine particles that fill the 

 space occupied by the body. The particles of some bodies 

 are held more closely together than are those of others, 

 and we express this difference by stating that some bodies 

 are more or less porous than others. 'A body whose 

 particles are not very close together is said to possess 

 porosity. Unglazed earthenware will absorb water. 



The property of a substance which enables it to withstand 

 long wear without decay or change is called durability. 

 Painted oak, for instance, is a very durable wood, as it will 

 stand a great deal of hard usage. 



A substance which resists heat and will melt only at a 

 high temperature is said to possess the property of in- 

 fusibility. Platinum possesses a higher degree of infusi- 

 bility than any other metal. The following table shows 

 the order of malleability, ductility, tenacity, and infusibility 

 of the most common metals. Those possessing these 

 properties to the highest degree appear at the tops of the 

 columns. 



