THE LIFE-WORK OF A CHEMIST. 497 



iug ou those changes which would occur more slowly during storage. 

 The application of a suitable temperature, the exclusion of outside con- 

 tamination, a microscopic examination of the "forced" beer, and the 

 knowledge which we owe to Pasteur of what the microscopic aspect 

 means, suffice to make each brewing foretell its own future history, and 

 thus suffice to avert the otherwise inevitable risks incident to the stor- 

 age and export of beer, the stability of which is unknown. 



Brewing has thus become a series of precise and definite oi)erations, 

 capable of control at every point. Instead of depending — as it had to 

 depend — on intuition and experience handed down in secrecy from 

 father to son, it now depends upon care, forethought, and the soundness 

 of the brewer's scientific training. This change in the nature of the 

 brewer's operations, and in the persons who govern them, is primarily 

 due to Pasteur. Other men have done much to carry on his work, but 

 it is to his example of ceaseless patience, and to his example of freely 

 publishing to the world all the results of his work, that the brewers of 

 all countries are indebted for the connection of each phenomenon with 

 a controllable cause, and for thus emancipating their industrj^ from em- 

 piricism and quackery. 



Much the same story has to be told about Pasteur's investigation of 

 wine and its diseases. As with the brewer, so with the wine-grower 

 Pasteur has pointed out the causes of his troubles, and the causes hav- 

 ing been ascertained, the remedies soon followed, and the practical 

 value of these researches to the trade of France and other wine-produc 

 ing countries has been enormous. 



The next labor of our scientific Hercules was of a diflerent kind, but of 

 a no less interesting or important character. The south of France is a 

 great silk-producing district. In 1853, the value of the raw silk was 

 represented by a sum of some £5,000,000 sterling, and up to that date 

 the revenue from this source had been greatly augmenting. Suddenly 

 this tide of prosperity turned, a terrible plague broke out amongst the 

 silk- worms, and in 1865, so general had the disease become, that the total 

 production of French silk did not reach £1,000,000, and the conse(|uent 

 poverty and suffering endured in these provinces became appalling. 

 Every conceivable means was tried to overcome the disease, but all in 

 vain. The population ajid the Government of France — for the evil was 

 a national one — were at their wits' end, and a complete collapse of one 

 of the most important French industries seemed inevitable. Under 

 these circumstances the great chemist Dumas, who was born at Alais, 

 in the center of one of the districts most seriously affected, urged liis 

 friend Pasteur to undertake an investigation of the subject. Pasteur, 

 who at this time had never seen a silk-worm, naturally felt diffident 

 about attempting so difficult a task, but at last, at Dumas's renewed en- 

 treaty, he consented, and in June, 1805, betook himself to the south for 

 tUe purpose of studying the disease on the spot. His previous training 

 here again stood him in good ste ul, and in September, 18G5, he was able 

 H. Mis. 221 32 



