FERMENTATION 23 



for practical work and conversation classes. . . . 

 It is delightful to see how keen we all are : 

 it goes so far that four of the Professors give 

 their written lectures, revised by themselves, to 

 a printer, who types them : he has already 120 

 subscribers for the course on applied mechanics, 

 and is printing 400 copies. ... I have what I 

 always longed for, a laboratory where I can go 

 at all hours, on the floor below my own room : 

 and sometimes, while I sleep often, these days 

 the gas is burning all night, and the processes are 

 going on of themselves. . . . Add to all this, that 

 I belong to two very active societies, and that I've 

 been appointed, by the General Council, to test 

 fertilisers for the Department of the North : rather 

 a heavy job, in this rich agricultural country, but 

 I took it gladly, to popularise and extend the 

 influence of our new Faculty. Don't be afraid that 

 it will all divert me from my beloved researches. 

 I shall not give up them. . . . Let's all work : 

 there's no amusement like work : that is what Biot 

 used to say, and he is an authority on this point." 



Beside lecturing, he would take students over 

 foundries and factories : and, in 1856, he took them 

 for a tour in Belgium, to see something of Belgian 

 industries. But the problems of fermentation were 

 always before him. In 1856, he was at work over 

 the manufacture of alcohol out of beet-sugar: in 

 1857, he gave to the Lille Scientific Society his 

 paper on the lactic-acid fermentation. He had 

 discovered, in sour milk, a trace of a greyish sub- 

 stance ; had proved it to be indeed a ferment of 



