LECTURE VI. 



BERZELIUS AND HIS CHEMICAL SYSTEM DULONG AND PETIT'S LAW 

 IsoMORrHisM PROUT'S HYPOTHESIS DUMAS' VAPOUR-DENSITY 

 DETERMINATIONS GMELIN AND HIS SCHOOL. 



BERZELIUS adopts dualism as the basis of his system. Even 

 before his time, the majority of compounds had been looked 

 upon as consisting of two parts. A uniform mode of regarding 

 them in this aspect became possible to a still greater degree in 

 the light of the electro-chemical phenomena, and it is the great 

 merit of Berzelius to have introduced this into the science and 

 to have established it. 



In his view, compound substances are produced by the 

 arrangement of the atoms side by side. 1 Compounds of the 

 first order are formed in this way from the smallest particles of 

 the elements ; these compounds give rise in turn to the forma- 

 tion of compounds of the second order ; and so on. Berzelius, 

 like his predecessors, seeks, in affinity, the reason for the com- 

 bination of two atoms, but this again is for him, as it was foi 

 Davy, a consequence of the electrical properties of the smallest 

 particles. He differs from Davy very essentially, however, in 

 the manner in which he assumes the electrical distribution. 

 But, quite apart from this, the two theories are not to be 

 compared as regards their importance for our science. Davy, 

 no doubt, advanced ingenious ideas as to the mode in which 

 he considered the chemical and electrical phenomena to Le 

 inter-related ; but from these hypotheses, by means of which a 



1 Essai sur la theorie des proportions chimiques et sur Pinfluence 

 chimique de 1'Electricite, 26. See also Berzelius, Lehrbuch der Chemie, 

 First Edition, Vol. 3, part I. Compare also Schweigger's Journal. 6 

 (1812), 119. 



