Comptes Rendus, a very remarkable paper on the changes which are produced in the power of thinking and observing by age. Fourcroy, the great animal chemist, who, in connection with Vauquelin, laid the foundation of that physiological chemistry on which the modern science is based; then Gay-Lussac, Thénard, and Dulong, men of the new science, who continued the work in a most glorious manner, which in this country had been carried to such a glorious issue by Humphry Davy—these men were at that time teaching at Paris, and at the laboratory which the liberality of the first Napoleon and his envy of English discoveries had established at L'École Polytechnique. They contiued to study and shape the new science which was destined to give to the modern science of chemistry precision.
Liebig then worked with Thénard, listened to Gay-Lussac's lectures, and he met there the young German chemists, Runge, well known by his many researches on tar, and the tar products; Mitscherlich, the discoverer of isomorphism and polymorphism; Gustav Rose, the representative of the perfection of analytical and inorganic chemistry. In 1823 he brought his first paper on the fulminates of silver and mercury before the Academy. And now, let me quote to you what he says of that event in the first work which he ever published. In the preface, which is a dedication to Alexander von Humboldt, he says that at the meeting of the Academy, on the 28th of July, 1823, he had read his paper, and was just engaged in packing up his apparatus and preparations, when a man, one of the members of the Academy, approached him, entered into conversation with him, and in an incredibly short space of time knew how to elicit from him all his hopes, schemes, and intentions. He did not dare to ask, either from shyness or from accident, who the gentleman was who spoke to him, and he disappeared again among the academicians. But he says: "From that day all the doors of society, and of all institutions, were open to me. I did not know until many years afterward to whom I owed this introduction and favor." It was to Humboldt, who had so well recommended him to the great French chemists that Gay-Lussac, who never took any pupil whatever into his laboratory, accepted him as his only pupil, and, more than that, joined with him in his continuation of those researches which at that early age he had brought to such perfection. This preface is beautiful in its conception and feeling, and has been printed in all the seven editions of the work which have since been published. If there were time this would, perhaps, be the place to show the wonderful influence which Humboldt has exercised upon the science of all countries; but I must pass over that subject, and continue the account of Liebig's life.
Through the recommendations of Humboldt and Gay-Lussac, both of which were addressed directly to the Grand-duke of Hesse-Darmstadt, Liebig was, at the age of twenty-one years, by the supreme will and absolute power of the grand-duke, appointed first Professor of
