Pasteur related all this in a vivid manner, evidently happy that his long and delicate laboratory researches should now pass into the domain of industry. He had been pleased to find that some Orleans wine merchants heated wine according to his advice in order to preserve it; and he now informed them that the temperature of 55° C. which killed germs and vegetations in wine could be applied with equal success to vinegar after it was produced. The active germs of the mycoderma aceti were thus arrested at the right moment, the anguillulæ were killed and the vinegar remained pure and unaltered. “Nothing,” concluded Pasteur, “is more agreeable to a man who has made science his career than to increase the number of discoveries, but his cup of joy is full when the result of his observations is put to immediate practical use.” This year 1867 marks a specially interesting period in Pasteur’s life. At Alais he had shown himself an incomparable observer, solely preoccupied with the silkworm disease, thinking, speaking of nothing else. He would rise long before anyone else so as to begin earlier the study of the experiments he had started, and would give his thought and attention to some detail for hours at a time. After this minute observation he would suddenly display a marvellous ingenuity in varying tests, foreseeing and avoiding causes of error, and at last, after so many efforts, a clear and decisive experiment would come, as it had done in the cases of spontaneous generation and of ferments. The contrasts in his mind had their parallel in his character: this usually thoughtful, almost dreamy man, absorbed in one idea, suddenly revealed himself a man of action if provoked by some erroneous newspaper report or some illogical statement, and especially when he heard of some unscrupulous silkworm seed merchant sowing ruin in poor _magnaneries_ for the sake of a paltry gain. When, on his return to Paris, he found himself mixed up with the small revolution in the Ecole Normale, he was seen to efface himself modestly before his masters when honours and titles came in question. Now he had interrupted his researches in order to do a kindness to the people of Orleans, who, practical as they were, and perhaps a little disdainful of laboratory theories, had been surprised to find him as careful of the smallest detail as they themselves were.