58 PASTEUR: THE HISTORY OF A MIND 



easy to be convinced that all Lavoisier's conclusions 

 were overthrown and that the work must be done again 

 or the conclusions revised. But as for Gay-Lussac 

 himself, so convinced was he of the truth of the interpre- 

 tation of Lavoisier that he contented himself with search- 

 ing whether the formula of the sugar, as determined by 

 his perfected method, would not accommodate itself so as 

 to break up into alcohol and carbonic acid. This was 

 to admit as exact the short-lived conclusion of Lavoisier. 

 But the proof very nearly succeeded. Believing that 

 Lavoisier was entirely right, Gay-Lussac did not hesitate 

 even to, give what is commonly called a coup de pouce, 

 and to modify from 2 to 3 per cent the figures which 

 his experiment had given him in order to make them 

 fit into the hypothetical outline traced by Lavoisier. 

 /* A singular spectacle ! the degree of confidence and security 

 of conscience to which a preconceived idea may lead! 

 A strange spectacle to see Gay-Lussac continue, but 

 happily only on this one point, the tradition of those 

 alchemists of -.the middle ages, who consented, it is true, 

 to inquire of experiment, but who did not question it 

 impartially, and listened only when it answered in ac- 

 cordance with their desires! 



Starting from an inexact experiment, supported by 

 the figures of an analysis voluntarily perverted, the idea 

 of Lavoisier nevertheless made its way, because of its 

 simplicity. It naturally met with more credence when 

 Dumas and Boullay observed in 1828 that every in- 

 correct statement in the interpretation of Gay-Lussac 

 could be made to disappear by admitting that the cane- 

 sugar assimilates the elements of a molecule of water 

 before undergoing alcoholic fermentation. This inter- 

 pretation, supported by experiment, reestablished both 

 the truth of the idea of Lavoisier and the accuracy of the 

 calculations of Gay-Lussac ; it had only one thing^against 



