No. 7.j WURTZ — THEORY OF ATOMS. 377 



an idea accordiDg to which all compound bodies are formed of 

 two immediate elements, which are either simple bodies or them- 

 selves compound bodies. 



This dualistic hypothesis was embodied, iu his time and with 

 his consent, in French nomenclature, the work of Guyton de 

 Morveau, the principle of which may be thus summarised : two 

 words to designate each compound, one to mark the genus, the 

 other the species. Thus, one of the fundamental conceptions of 

 the system of Lavoisier — dualism in combinations — found a 

 striking expression in the binary structure of the names, and is, 

 as it were, insinuated into the mind by the very terms of chemi- 

 ciil language; and we know what is, in such a case, the power 

 of words. 



The great successor of liuvoisier, Berzelius, extended to the 

 whole of chemistry the dualistic hypothesis of Lavoisier on the 

 constitution of salts. "Wishing to give it a solid support, he 

 added to it the electro-chemical hypothesis. All bodies are for- 

 med of two constituent parts, each of which possesses, and is, 

 as it were, animated by, two electric fluids. And as the electro- 

 positive fluid attracts the electro-negative, it is natural, it is 

 necessary that in every chemical compound the two elements 

 should reciprocally attract each other. Is not the one carried 

 towards the other by electric fluids of opposite kinds? We see 

 that the hypothesis] of Berzelius gives at once a striking inter- 

 pretation of the dualism in combinations and a simple and pro- 

 found theory of chemical afl&nity. This elective attraction which 

 the final particles of matter exercise upon each other was refer- 

 red to electric attraction. 



Another theoretic conception gave a body to the electro-chemi- 

 cal hypothesis, and has given since a solid basis to chemistry as 

 a whole. We speak of the atomic theory, revived from the 

 Greeks, but which took, at the commencement of this century, 

 a new form and a precise expression. It is due to the penetra- 

 tion of an English thinker, a teacher of chemistry in Manchester 

 in the beginning of the century. It was less a pure speculation 

 of the mind, as were the ideas of the ancient atomists and of the 

 philosophers of the Castesian school, than a theoretical repre- 

 sentation of well-established facts, viz., the parity of the pro- 

 portions according to which bodies combine, and the simplicity 

 of the relations which express the multiple combinations between 

 two bodies. 



