The Evolution of the Sciences 



it might be added that every forward step made 

 by this science is connected with the intro- 

 duction of some new physical apparatus: the 

 calorimeter and the thermometer identified with 

 Lavoisier, Berthelot, Raoult; the manometer 

 with Gay-Lussac and Sainte-Claire Deville; 

 the electric current with Davy and Moissan; 

 the spectroscope with Kirchhoff and Bunsen; 

 the polarimeter with Biot and Faraday; the 

 electroscope with Curie. 



With its growth chemistry has lost its 

 object, because to-day nobody can define, with 

 accuracy, the purpose of its researches. It no 

 longer places that purpose in the study of 

 chemical species; it is now the business of physics 

 or mineralogy to tell us that chlorine is a liquifi- 

 able gas, or that sulphur is an octahedral crystal. 

 And if, to be more logical, we define chemistry 

 as the study of reactions, we find it impossible 

 to tell where the reaction finishes and the 

 physical phenomenon commences. If it be 

 said that the former involves permanent change, 

 while the latter does not, the magnetisation 

 of steel would forthwith become a chemical 



phenomenon, because it survives the cause 



56 



