A BRIEF SKETCH 



MODERN THEORY OF CHEMICAL TYPES. 



BY CHARLES M. WETHERILL, PH. D., M. D. 



After the electric current had been applied to the decomposition of inorganic 

 bodies, and it had been discovered that hydrogen, the metals, and the bases 

 appeared at the negative pole, while oxygen, chlorine, and the acids were mani- 

 fested at the positive pole, the assumption that electrical attraction Avas the 

 bond of union in chemical combinations was very natural, and the electro- 

 chemical theory growing out of these experiments became speedily adopted by 

 chemists. The theory explained satisfactorily all known phenomena ; it gained 

 additional support from the discovery that the chemical elements and com- 

 pounds were separated by electricity from their combinations in the ratio of 

 their equivalents. In those days it was assumed, and at the present time it 

 is manifest, that any theory not embracing organic as well as inorganic com- 

 pounds would be untenable, and hence arose the radical theory, first applied 

 to inorganic salts, but afterwards thoroughly studied and developed in respect 

 to organic compounds. 



As the present sketch is intended less for chemists than for others who may 

 be confused at the appearance of the formulae of organic compounds given iu 

 modern chemical essays, the author may be pardoned iu citing facts and 

 formulae trite to chemists. He would also take occasion here to accredit to the 

 Lehrbuch of Graham Otto many of the illustrations, as well as some of the 

 ai'guments, employed in the present sketch. 



The nature of electrical attraction renders the idea of hinary compounds in 

 chemi.stry imperative, if we assume that electricity is the bond of union in such 

 compounds. 



Berzelius imagined the elementary atoms laden with electricity and with 

 positive and negative poles, but so that in the atom of one element the positive 

 electricity predominated, while in that of another element the negative elec- 

 tricity was in excess. This excess of (+ or — ) electricity communicated its 

 characters to the clement, making it positive or negative. If two atoms of dif- 

 ferent electrical character are brought sufficiently near to each other, they 

 mutually attract each other, forming a compound atom, which is itself positive 

 or negative according to the predominance of one kind or the other of its 

 electricity. The new compound atom was, therefore, susceptible of further 

 attraction by another compound atom of diflPerent electricity, and so on, the 

 attraction becoming weaker as the compound atom becomes more complex. 



Ampere imagined the atoms of positive elements to have positive nuclei with 

 negative atmospheres or envelopes, and atoms of the negative elements to have 

 negative nuclei and positive envelopes. Hence a positive and a negative atom 

 upon coming together would mutually polarize each other ; the -\- and — E of 

 their nuclei would draw them together to form a compound, and the i E of 



