Pasteur had formerly demonstrated that if a putrescible liquid, such as beef broth for instance, after being previously boiled, is kept in a vessel with a long curved neck, the air only reaching it after having deposited its germs in the curves of the neck, does not alter it in any way. He now desired to invent an apparatus which would protect the wort against external dusts, against the microscopic germs ever ready to interfere with the course of proper fermentation by the introduction of other noxious ferments. It was necessary to prove that beer remains unalterable whenever it does not contain the organisms which cause its diseases. Many technical difficulties were in the way, but the brewers of Chamalières tried in the most obliging manner to facilitate things for him. This exchange of services between science and industry was in accordance with Pasteur’s plan; though he had been prophesying for fourteen years the great progress which would result from an alliance between laboratories and factories, the idea was hardly understood at that time. Yet the manufacturers of Lille and Orleans, the wine merchants and the silkworm cultivators of the South of France, and of Austria and Italy, might well have been called as enthusiastic witnesses to the advantages of such a collaboration. Pasteur, happy to make the fortune of others, intended to organize, against the danger of alterations in beer, some experiments which would give to that industry solid notions resting on a scientific basis. “Dear master,” wrote he to J. B. Dumas on August 4, 1871, from Clermont, “I have asked the brewer to send you twelve bottles of my beer.... I hope you will find it compares favourably even with the excellent beer of Paris cafés.” There was a postscript to this letter, proving once more Pasteur’s solicitude for his pupils. “A thousand thanks for your kind welcome of Raulin’s work; Bernard’s support has also been promised him. The Academy could not find a better recipient for the prize. It is quite exceptional work.” Pasteur, ever full of praises for his pupil, also found excuses for him. In spite of M. Duclaux’s pressing request, Raulin had again found reasons to refuse an invitation to come to Auvergne for a few days. “I regret very much that you did not come to see us,” wrote Pasteur to Raulin, “especially on account of the beer.... Tell me what you think of doing. When are you coming to Paris for good? I shall want you to help me to arrange my laboratory, where everything, as you know, has still to be done; it must be put into working order as soon as possible.” Pasteur would have liked Raulin to come with him to London in September, 1871, before settling down in Paris.