86 HISTORY OF CHEMISTRY. [LECTURE VI. 



number of facts could be most excellently explained, he never 

 succeeded in producing a theory which might serve as the 

 foundation of a chemical system. Berzelius was the first to do 

 this. He made it his life's task to establish in chemistry a 

 uniform system which should be applicable to all the known 

 facts and he accomplished it. Hence his views are of far 

 greater importance in the development of chemistry than those 

 of Davy are. 



According to Berzelius, it is not only when two substances 

 are brought into contact that electricity is generated, but it is 

 a property of matter; and in every atom, two oppositely 

 electrical poles are assumed. 2 These poles do not, however, 

 contain equal quantities of electricity. The atoms are unipolar, 

 the electricity of the one pole predominating over that of the 

 other; and thus every atom (and therefore every element) 

 appears to be either positively or negatively electrical. In this 

 respect it is possible to arrange the elementary substances into 

 a series, so that each member is always more electro-negative 

 than the next succeeding one. Oxygen stands at the top, and 

 is absolutely electro-negative, 3 while the other substances are 

 only relatively positive or negative according as they are com- 

 pared with elements which come before them or after them 

 in the electrical series. This series does not constitute a table 

 of affinities in the Geoffrey- Bergman sense ; and it does not 

 express the affinity of the individual substances for oxygen, for 

 example. Berzelius has not forgotten Berthollet's teaching, 

 that affinity is not of a constant character and independent of 

 the physical conditions; as he supposes this unipolarity to be ; 

 and he is also well aware that oxygen can be removed from 

 metallic oxides by carbon or sulphur, that is to say, by other 

 electro-negative substances. With him, affinity depends princi- 

 pally upon the intensity of the polarity, i.e., upon the quantity 

 of electricity which is contained in the two poles. This is 

 variable, however, especially with changes of temperature. 



- Essai etc. 85. 3 In Schweigger's Journal. 6, 129, where he states his 

 electro-chemical theory in detail, Berzelius calls oxygen electro-positive. 



