Footnote 155: FREMY, _Comptes rendus de l’Académie_, vol. lviii. p. 1065, 1864. Footnote 156: See our Memoir of 1860 (_Annales de Chimie et de Physique_, vol. lviii.) p. 61, and following, and especially pp. 69 and 70, where the details of the experiment will be found. Footnote 157: PASTEUR, _Comptes rendus de l’Académie des Sciences_, vol. lxxiii. p. 1419, 1871. Footnote 158: In his Memoir of 1870, Liebig has made a remarkable admission: “My late friend Pelouze,” he says, “had communicated to me, nine years ago, certain results of M. Pasteur’s researches on fermentation. I told him that, just then, I was not disposed to alter my opinion on the cause of fermentation, and that if it were possible by means of ammonia to produce or multiply the yeast in fermenting liquors, industry would soon avail itself of the fact, and that I would wait to see if it did so; up to the present time, however, there has not been the least change in the manufacture of yeast.” We do not know what M. Pelouze’s reply was; but it is not difficult to conceive so sagacious an observer remarking to his illustrious friend, that the possibility of deriving pecuniary advantage from the wide application of a new scientific fact had never been regarded as the criterion of the exactness of that fact. We could prove, moreover, by the undoubted testimony of very distinguished practical men, notably by that of M. Pezeyre, director of distilleries, that upon this point also Liebig was mistaken. Footnote 159: PASTEUR, _Comptes rendus de l’Académie_, vol. lxxviii. pp. 213-216. Footnote 160: TRÉCUL, _Comptes rendus de l’Académie_, vol. lxxviii. pp. 217, 218. Footnote 161: See on this subject the verbal observations which we addressed to the Academy of Sciences, at its meetings of April 10th and 24th, 1876. CHAPTER VII. New Process for the Manufacture of Beer. The principles established in the course of this work implicitly involve the conditions of a new process of manufacture, the essential feature of which would consist in the production of a beer of excellent keeping qualities, we might even say a beer that could not undergo alteration. It will not be difficult now to make ourselves clear on the point.