3S4 THE CANADIAN NATURALIST. [Yol. vii. 



l>odies contains. But what ! is this merely an ingenious exercise 

 of the mind ? and the construction of formulas by means of these 

 symbolic materials which are selected, which are arranged so as 

 to give to the molecular edifice a determined form, — is this a 

 mere matter of curiosity? By no means. These formulae, by 

 whose aid are expressed the composition of bodies and the con- 

 stitution of their molecules, offer also a valuable aid for the 

 interpretition of their properties, for the study of their metamor- 

 phoses, for the discovery of their reciprocal relations, — all things 

 which are intimately connected in each body with the nature 

 and arrangement of the atoms. Now, the investigation and com- 

 parison of these formulas furnish to the inquiring spirit the ele- 

 ments of a powerful synthesis. What treasures have been 

 acquired by science by this process, which consists in deducing 

 the transformations of bodies from their molecular structure, and 

 in creating^ by a sort of intuition, new molecules by means of 

 those already known ! The artificial formation of a number of 

 combinations, the syntheses of as many organic compounds as 

 nature alone seemed to have the privilege of forming — in a word, 

 the greater part of chemical discoveries which have enriched 

 science and the world for twenty years — are founded on this 

 inductive method, the only efficacious and the only rational one 

 in the sciences. I shall cite only one example among many 

 others. 



A happy chance led to the discovery of that brilliant substance, 

 of a bright purple, which is known under the name of fuchsine 

 or rosaniline. Analysis determines its composition, skilled inves- 

 tigations find its molecular structure. Soon it is known how to 

 modify it, to multiply the number of its derivatives, to vary the 

 sources of their production, and from attentive study of all these 

 reactions, issue a pleiad of analogous substances whose diverse 

 colours rival in brilliancy the richest tints of the rainbow. A 

 new and powerful industry has already resulted from all these 

 investigations, which theory has followed step by step and guided 

 the fertile evolution. In this order of investigation, science has 

 recently gained one of her most striking triumphs. She has 

 succeeded in forming at once the colouring matter of madder 

 (alizarin). By an ingenious combination of reactions, and by 

 theoretic reasonings still more ingenious, MM. Graebe and 

 ].iebermann have succeeded in obtaining this body synthetically, 

 by means of anthracene, one of the numerous bodies which is 



