COMPOSITION OF MATTER 3 



is often dependent upon a physical change, and a physi- / 

 cal change is, in turn, often dependent upon a chemical 

 change. A chemical change necessarily brings about a 

 physical change. While the sciences of chemistry and 

 physics are, to a certain extent, closely related, each 

 nevertheless deals with a different phase of change which 

 matter undergoes. 



4. Indestructibility of Matter. When either a chem- 

 ical or physical change takes place, no matter is destroyed 

 or produced. It is not possible either to create or destroy 

 matter. This is known as the law of indestructibility oj 

 matter. 



Whenever a chemical change takes place, the parts 

 which make up the substance are rearranged in a new and 

 different way, or they are combined with other materials. 

 When wood is burned, it is changed into gaseous prod- 

 ucts and ashes ; the materials which composed the wood 

 are not lost to nature, they simply assume a different 

 form. The law of indestructibility of matter is one of the 

 foundation principles of chemistry. It was believed, at 

 one time, that metals, as copper, could be changed into 

 gold, and other substances into different forms of matter. 

 After many centuries of experimenting, it was found 

 that this could not be done, and as the result, the law of 

 indestructibility of matter was established. 



5. flolecules. It is possible, by mechanical means, as 

 pulverizing, to reduce substances to a very fine state of 

 division, and it is believed that if this division could be 

 carried on by more refined methods, particles of mat- 

 ter could finally be obtained that would not be suscepti- 



