34 THE LIFE OF PASTEUR 



Laurent was appointed as Dumas' assistant at the Sorbonne. 

 Pasteur did not dwell upon his own disappointment, but 

 rejoiced to see honour bestowed upon a man whom he thought 

 worthy of the first rank. Some judges have thought that 

 Laurent, in his introductory lesson, was too eager to expound 

 his own ideas ; but is not every believer an apostle ? When a 

 mind is full of ideas, it naturally overflows. It is probable 

 that Pasteur in Laurent's place would have kept his part as 

 an assistant more in the background. He did not give vent to 

 the slightest criticism, but wrote to Chappuis. "Laurent's 

 lectures are as bold as his writings, and his lessons are making 

 a great sensation amongst chemists." Whether one of 

 criticism or of approbation, this sensation was a living element 

 of success. In order to answer some insinuations concerning 

 Laurent's ambition and constant thirst for change, Pasteur 

 proclaimed in his thesis on chemistry how much he had been 

 " enlightened by the kindly advice of a man so distinguished, 

 both by his talent and by his character." 



This essay was entitled " Researches into the saturation 

 capacity of arsenious acid. A study of the arsenites of potash, 

 soda and ammonia.' 9 This, to Pasteur's mind, was but school- 

 boy work. He had not yet, he said, enough practice and 

 experience in laboratory work. "In physics," he wrote to 

 Chappuis , "I shall only present a programme of some re- 

 searches that I mean to undertake next year, and that I merely 

 indicate in my essay." 



This essay on physics was a " Study of phenomena relative 

 to the rotatory polarization of liquids." In it he rendered full 

 homage to Biot, pointing out the importance of a branch of 

 science too much neglected by chemists ; he added that it was 

 most useful,, in order to throw light upon certain difficult 

 chemical problems, to obtain the assistance of crystallography 

 and physics. " Such assistance is especially needed in the 

 present state of science." 



These two essays, dedicated to his father and mother, were 

 read on August 23, 1847. He only obtained one white ball and 

 two red ones for each. " We cannot judge of your essays," 

 wrote his father, in the name of the whole family, " but our 

 satisfaction is no less great. As to a doctor's degree, I was far 

 from hoping as much ; all my ambition was satisfied with the 

 agregation." Such was not the case with his son. 



