THE ATOMIC VIEW OF NATURE. 



405 



simple and plausible, governed research for a long period, 

 but has finally been abandoned as insufficient/ 



Another blow was dealt at the simple theory by which Discovery of 



isomerism. 



^ The electro-chemical theory of 

 Davy and Berzelius was, after about 

 fifteen years of development, during 

 which period the use of the signifi- 

 cant terms electro - positive and 

 electro-negative was not consistent, 

 finally enunciated bj^ Berzelius in 

 1818 in his ' Essay on the theory of 

 Chemical Proportions and on the 

 Chemical Action of Electricity.' 

 From that time it reigned almost 

 supreme for twenty years, when 

 both physical and chemical dis- 

 coveries began to show its insuffici- 

 ency. A very concise account of it 

 is given in Kopp's ' Entwickelung 

 der Chemie,' and in E. von Meyer's 

 ' History of Chemistry,' translated 

 bj' M'Gowan (Macmillan & Co., 

 1891). Berzelius clung to it to the 

 last, and at the present moment 

 there exists a widespread opinion 

 that the future will see a revival 

 and modified acceptance of the 

 Davy -Berzelius theory. In rela- 

 tion to this Helmholtz's celebrated 

 Faraday lecture of the year 1881 

 should be read (see the reprint in 

 Helmholtz's ' VortrJige und Reden,' 

 vol. ii.) The jDeculiarity of the elec- 

 tro-chemical theory was that it was 

 an atomic theory as well as a theory 

 of chemical affinity. When it was 

 abandoned, the two distinct in- 

 terests, that of developing the 

 atomic view, so as to give a correct 

 description of the constitution of 

 chemical compounds and reactions, 

 and that of giving an explanation 

 of chemical affinity, fell for a time 

 asunder. The former interest pre- 

 ponderated, owing mainly to two 

 reasons, the one theoretical, the 

 other practical. The theoretical 

 reason was the need of a difierent 

 method of systematicallj^ arranging 

 the chaos of new organic compounds 



with which chemistry became 

 crowded about the year 1840. 

 Berzelius had created the nomen- 

 clature and notation of chemistry ; 

 but this proved insufficient to de- 

 scribe and grasp the processes and 

 products of the many carbon com- 

 pounds. The practical reason which 

 cast into the background the study 

 of chemical affinity and its nature 

 was the growing demands of manu- 

 facturing chemistry. This was 

 during a long period occupied 

 mainly with the analysis and syn- 

 thesis of new products, or with new 

 and simpler methods for producing 

 well-known compounds. The study 

 of reactions and of the products of 

 bodies was practically of more in- 

 terest than that of the forces which 

 governed them. The question of 

 the cost of producing chemical pro- 

 ducts was for a long time a second- 

 ary one. Towards the end of our 

 century both theoretical and prac- 

 tical considerations forced upon 

 chemists the necessity of making 

 themselves acquainted with the 

 different forms of energy which are 

 at our command in chemical as well 

 as in mechanical operations, and 

 this has led to a renewal of the 

 study of chemical and mechanical 

 energy, and of the nature and laws 

 of chemical affinity. Economy in 

 practical chemistry can be divided 

 into two branches : the economy of 

 materials and the economy of 

 energy. The great developments 

 in the course of this century have 

 consisted largely in utilising by- 

 products and in avoiding waste of 

 substance. We are now only ap- 

 proaching the second problem : 

 how to put the energy which is at 

 our command to the best use. 



