218 MODERN SCIENCE READER 



DUALISM. On the basis of his electrolytic investigations 

 Davy also constructed an electro-chemical theory which 

 was subsequently modified and extended by Berzelius. 

 According to Davy (1807) when the atoms of different ele- 

 ments come into contact, they become charged with the 

 opposite forms of electricity, by whose attractive force they 

 are held together, constituting chemical compounds. Ber- 

 zelius' theory was as follows: "The atom of each element 

 does not become charged with electricity on coming in con- 

 tact with other atoms, but is charged, whether combined 

 with other atoms or not. With respect to the electrical 

 charges of their atoms, the elements form an 'electro-chem- 

 ical order,' oxygen being about the most electro-negative, 

 potassium the most electro-positive of elements. All bases 

 are produced by the combination of oxygen with electro- 

 positive elements and all acids by the combination of 

 oxygen with electro-negative elements. Yet bases and acids 

 are not altogether neutral, in the former positive electricity, 

 in the latter negative electricity, predominates. This is 

 why bases and acids show no mutual chemical indifference, 

 but combine to form salts. When the terminals of a suf- 

 ficiently powerful galvanic battery are immersed in the 

 solution of a salt, the base of the latter is attracted more 

 strongly by the negative terminal than by the acid; and 

 the acid is attracted more strongly by the positive terminal 

 than by the base; hence electrolysis ensues, the base being 

 deposited on the negative, the acid on the positive, term- 

 inal." In brief, Berzelius maintained (1) that oxygen is 

 an indispensable constituent of bases, acids and salts; (2) 

 that bases, acids and salts have a dual constitution, each 

 being made up of an electro-positive and an electro-nega- 

 tive part; (3) that chemical affinity is nothing but the 

 mutual attraction of opposite forms of electricity. In the 

 first of these principles Berzelius followed Lavoisier, for 

 years refusing to accept Davy's view that chlorine and 

 nitrogen were elements, and that their compounds with 

 hydrogen namely hydrochloric acid and ammonia al- 



