88 Mr. M. M. Pattison Muir o/i Che^nical Classificatimi. 



posed ? The futile attempts of the alchemist to found a science 

 naturally led those who were the authors of the true chemistry 

 to disparage the method of their predecessors to an extreme 

 degree. Nothing was to be hoped for from a desultory gather- 

 ing together of innumerable reactions ; the quantitative study 

 of the composition of substances appeared to promise brilliant 

 results : hence Lavoisier tended to overlook the quantitative 

 study of reactions^ while paying all regard to the quantitative 

 study of the composition of bodies. This disregard of reac- 

 t'ons was carried to its extreme by Berzelius and his school, 

 and found its full development in a theory which was always 

 ready, with its compound radicles and its copulas, to give 

 the correct constitutional formula for each new substance as 

 soon as it was discovered, without w^aiting for the tedious 

 detail of reactions and decompositions, which, if not in keep- 

 ing with the theoretically deduced formula, were to be re- 

 garded as the products of a disordered brain*. 



But it was impossible that a true classification could be based 

 upon such one-sided views as those of Berzelius and the up- 

 holders of the dualistic school. They had done their work in 

 advancing the knowledge of the empirical composition of com- 

 pounds, in determining with accuracy the combining-num- 

 bers of many elements, in insisting upon the aid to be de- 

 rived from a knowledge of the composition of substances 

 in forming a system of classification, and perhaps in paving 

 the way for the subsequent conception of compound radicles. 



8. The experiments of Dumas upon acetic and chloracetic 

 acids mark the rise of the modern school of chemistry and 

 of the modern systems of classification. 



Dumas found that chlorine reacts upon acetic acid to form 

 a substance possessed of many of the properties of the original 

 acid, but nevertheless containing chlorine. The dualistic 

 school interpreted the results of the analyses of acetic and 

 chloracetic acids as pointing to entirely different constitutional 

 formulae for these bodies. If this be so, replied Dumas, 

 whence comes the extreme similarity of properties? We 

 have in this reasoning of Dumas a distinct partial return to 

 the older ideas of the predecessors of Lavoisier. Function 

 again begins to assume importance in classificatory schemes. 



Dumas, Laurent, Gerhardt, and their followers founded 

 the new school of Substitutionists as opposed to the upholders 

 of Dualism. The new school regarded the chemical mole- 

 cule as one whole, parts of which might be sometimes with- 

 drawn and their place taken by other parts without disturb- 

 ing the stability of the building. Hence the idea of com- 



* See Laureut, * Chemical Method," Cavendi&'h-Sociely Ed., p. 32 &c. 



