Xll 



half a century was to remain the standard text-book on physics, had 

 just appeared, and Dumas had found, more especially in the first 

 volume, plenty of subjects directing his attention to the art of 

 experimenting, of making observations, of consulting nature, and of 

 discovering the laws of her phenomena. The " Annales de Chimie " 

 offered him, moreover, splendid models in the papers of Berzelius, 

 Davy, Gay-Lussac, and Thenard. At the same time he studied 

 with indefatigable zeal the works of Lavoisier, and the " Statique 

 Chimiqne " of Berthollet. 



Dumas was then eighteen years of age. It was about that time 

 that he had the good fortune to make himself useful to one of the 

 principal physicians of the town, a circumstance which contributed 

 not a little to advance him in the circles in which he had hitherto 

 lived. Dr. Coindet asked him to examine some carbonised sponges, 

 and to ascertain more especially whether iodine was present in them. 

 Having after some days received an affirmative answer, Dr. Coindet 

 no longer hesitated to consider iodine a specific against goitre. Dumas 

 was then asked to give his attention to the subject and to point out 

 the preparations in which iodine might be most conveniently admin- 

 istered. He suggested tincture of iodine, potassic iodide, and iodised 

 potassic iodide. Soon afterwards these new remedies were mentioned 

 in a German journal published at Zurich, and it is in this connexion 

 that the name of Dumas is first met with in scientific literature. 



About that time Dr. J. L. Prevost, after an absence of several years, 

 returned to Geneva. He had long been resident in Edinburgh and 

 Dublin, devoting himself to comprehensive studies in the several 

 departments of medicine. Among these was a particular examina- 

 tion of the physiological effects of digitalis, and he was naturally 

 anxious to obtain the active principle of the plant free from all 

 foreign matter accompanying it. He invited Dumas to join him in 

 this inquiry. The problem to be solved consisted in successively 

 removing all that appeared inert so as to concentrate the active con- 

 stituent, which would ultimately remain in a state of purity. The 

 chemical properties of this principle being unknown, the only means 

 of estimating the concentration was to observe the effect of the con- 

 centrated substance upon animals. This slow and irksome process 

 of elimination did not lead to any result ; it is well known that the 

 isolation of digitaline was not effected until some years later. But 

 however unsuccessful, these joint labours gave rise to a far more 

 fruitful collaboration. 



Whilst studying together the physiology of Bicherand, a work then 

 in great repute, and the memoirs of Magendie, which were beginning 

 to attract increased attention, the two friends resolved to engage in a 

 series of chemico-physiological researches. 



It seemed natural enough to commence these researches by a 



