course he is approachable, kind, ready for a pleasantry, a laugh, or to impart from the great store of his learning whatever the earnest inquirer may need. In the lecture-room his talk is so simple and familiar that the most abstruse principles seem like every-day facts; and his illustrations, drawn from the ordinary and homely experiences of common life, are so clear, pat, and to the point, that one can neither fail to feel their force nor forget their application. With farmers, be they great landholders or humble peasants, his information and explanations are always plain, attractive, practical, and suited to the occasion and the men. And everywhere he is the earnest, laborious, learned, and reverent student, the kindly, faithful instructor, and the worthy man.
Among the especial services Stöckhardt has rendered as teacher and promoter of science is one which, perhaps, is best illustrated in his text-book of chemistry ("Schule der Chemie"), the setting forth of the idea that the right way to teach science is by bringing the student into direct contact with nature, by making him an observer, an investigator, and thus his own best teacher. In the preface to the twelfth edition of this book, he says:
Accordingly the book abounds with simple experiments to be made with apparatus which any student may get and handle, and is yet sufficient to illustrate, enforce, and impress the truths that are taught, and, what is better, to enable the learner to find the highest inspiration in working out the truths himself. How useful this system of instruction, as thus set forth by Stöckhardt, has proved, may be inferred from the wide circulation of the book as mentioned above, and the facts that sets of apparatus put up to go with it were sent to all parts of Germany, to England, and to Russia, and that a depot for their sale was established in New York.
Of Stöckhardt's greatest work, the promotion of agricultural science, perhaps the best idea may be got from his "Chemical Field Sermons," which show his methods of popularizing science, and especially from his journal, "Der chemische Ackersmann," in which both his popular treatises and his scientific investigations have been published.
As a discoverer, Stöckhardt, though well known, is outranked by other agricultural chemists of his time. Liebig, the father of agricultural chemistry, Wolff, Henneberg, Knop, Nobbe, Stohmann, Kühn, and others in Germany, Boussingault in France, and Lawes and Gil-