INTRODUCTION 



the false but plausible theory of Phlogiston interpos- 

 ing, and delaying for generations the true explanation 

 of combustion, of respiration, and of numerous other 

 phenomena that are connected with free oxygen and 

 with its many compounds. 



Upon the knowledge obtained through the Science 

 of CHEMISTRY nearly all the progress made in other 

 sciences depends. Through it we have learned of 

 what the animal, plant and mineral realms are made, 

 of what our globe is composed, and, most wonderful 

 of all, with the help of spectral analysis, we are 

 taught whether the far distant stars are moving towards 

 us or away from us, of what elements these glowing 

 orbs are composed, and we have even discovered in 

 the sun certain elements before they were known or 

 met with on this earth. Chemistry has also proved 

 to us the indestructibility of Matter. We can make 

 or break up many compounds ; they are groupings of 

 atoms into molecules that can be separated again into 

 atoms, but the atoms can neither be made nor can 

 they be destroyed. They are imperishable. In like 

 manner Energy can neither be made nor can it be de- 

 stroyed. The changes that can be induced in its 

 form or manifestations are endless, but man cannot 

 bring it into being from nothing, nor can he annihil- 

 ate it. 



Any change in chemical combinations is always 



(xix) 



