THE PROPERTIES OF MATTER. 7 



sulphur. Heat it in a spoon, and it assumes the liquid 

 form, but it is sulphur yet. In none of these changes has 

 the nature of the molecule, or the identity of the sub- 

 stance, undergone any change. On the other hand, if 

 the sulphur be heated sufficiently it will take fire and 

 burn, producing the irritating, suffocating gas familiar to 

 all through the use of common matches. We thus see 

 that the sulphur is combustible. This combustibility is 

 a chemical property, in the manifestation of which the 

 identity of the substance is destroyed. Before the mani- 

 festation we had sulphur; after it we have sulphurous 

 anhydride (S0 2 ). The original molecules were elemen- 

 tary, composed of like atoms ; the resultant molecules 

 are compound, composed of unlike atoms, sulphur and 

 oxygen. 



17. Division of Physical Properties. Physi- 

 cal properties of matter are, in turn, divided into two 

 classes, universal and characteristic. 



18. What are Universal Properties ? Uni- 

 versal properties of matter are such as belong to 

 all matter. 



All substances possess them in common ; no body 'can 

 exist without them. We cannot even imagine a body 

 that does not require space for its existence. This qual- 

 ity of matter, which will so&i be named, is, therefore, 

 universal. 



19. What are Characteristic Properties? 



Characteristic properties of matter are such as 

 belong to matter of certain kinds only. 



They enable us to distinguish one substance from an- 



