Proceedings of the Belfast Natural History and Philosophioal Society, 1920-1921. 



19th and ^Oth November, 3rd and 10th December, 1920 



Professor Gregq Wilson, President of the Society, 

 IN THE Chair. 



A Course of four Lectures on 



THE GROUNDWOPvK OF THE UNIVERSE FROM A 

 CHEMICAL STANDPOINT, 



By Professor A. W. Stewart, D.Sc, 



Profesfior of Chemistry, Queeyis University, Belfast. 



In Chemical Lecture Theatre, Queen's University. 



I.— THE FOUNDATION STONES OF MATTER. 



One of the common actions of the human mind is the search 

 for intrinsic resemlilances between things which on the surface 

 exhibit differences in character. Thus the chemist seeks to 

 identify common characteristics in a group of materials, each of 

 which differs from the others in its surface appearance. The 

 great aim of the chemist is simplification, the breaking up of 

 matter into forms which cannot be further decomposed. Thus 

 water can be decomposed into two gases, oxygen and hydrogen, 

 and neither of these gases has been further decomposed, so they 

 are called "Elements," and to-day we recognise ninety-two such 

 " Chemical Elements " as capable of existence. These elements 

 are built up of particles called atoms, almost indefinitely small, 

 the atoms in any one element being all alike in chemical properties; 

 but the different chemical elements vary because of the different 

 characters of the atoms from which they are formed. 



Since these atoms are material bodies, they niust have definite 



