20 ILLINOIS ACADEMY OF SCIENCE. 



Dr. S. A. Forbes gave a verbal report for the Committee on 

 Ecological Survey. 



The remainder of the afternoon was occupied with further 

 scientific papers. 



On motion, duly seconded, the fourth annual meeting of the 

 Illinois xA.cademy of Science adjourned. 



The President's Address 



THE ELECTRON THEORY. 



W. A. NOYES. 



The first fairly comprehensive theory of chemical combination 

 which bears some relation to modern views was proposed in a 

 rather informal way by Lavoisier. Shortly after Priestly had dis- 

 covered "dephlogistigated air," in 1774, the great French chemist 

 came to recognize very clearly the fundamental part which the 

 newly discovered element plays in nature. Finding that it is an 

 essential element in the acids formed by the combustion of sul- 

 phur, phosphorus, nitrogen and carbon, he called it oxygen — the 

 acid-former — a name still appropriate, though I think that most 

 chemists to-day do not recognize how appropriate, so clearly as 

 did the chemists who lived a century ago. Lavoisier also recog- 

 nized that oxygen combines with metals to form what were then 

 called metallic calxes, and with the assistance of De Morveau and 

 others a nomenclature was introduced which was based on the 

 view that the oxides of the non-metallic elements, called acids, 

 combine with the oxides of the metallic elements, which had been 

 called calxes, to form salts. This nomenclature still clings to us 

 in such names as sulphate of potash. The thought expressed in 

 this nomenclature, that there is a dual nature in the salts, fur- 

 nished a very natural basis from which the electrochemical theory 

 of Davy and Berzelius was easily developed. According to this 

 theory, the atoms of the elements have two electrical poles, one 

 positive and one negative, and the properties of the element depend 

 upon whether the one or the other of these poles contains more 

 electricity, chemical combination depending on the discharge of 

 two poles of opposite signs when the atoms of two elements come 

 together, the heat of combination being caused by this discharge. 

 The resulting compound may still have an excess of positive or 



