A TREATISE ON THE CHEMICAL COMPOSITION, STRUCTURE, FOR ALL STUDENTS OF AGRICULTURE. WITH NUMEROUS ILLUSTRATIONS AND TABLES OF ANALYSES. BY SAMUEL W. JOHNSON, M. A., PROFESSOR OF ANALYTICAL AND AGRICULTURAL CHEMISTRY IN THE SHFFIELD NEW YORK: ORANGE JUDD & COMPANY, 245 BROADWAY. Entered according to Act of Congress, in the year 1868, by ORANGE JUDD & CO., At the Clerk's Office of the District Court of the United States for the Southern District of New-York, LOVEJOY, SON & Co., ELECTROTYPERS & STEREOTYPERS, 15 Vandewater Street, N. Y. 1702 PREFACE. For the last twelve years it has been the duty of the writer to pronounce a course of lectures annually upon Agricultural Chemistry and Physiology to a class in the Scientific School of Yale College. This volume is a result of studies undertaken in preparing these lectures. It is intended to be one of a series that shall cover the whole subject of the applications of Chemical and Physiological Science to Agriculture, and is offered to the public in the hope that it will supply a deficiency that has long existed in English literature. The progress of these branches of science during recent years has been very great. Thanks to the activity of numerous English, French, and especially German investigators, Agricultural Chemistry has ceased to be the monopoly of speculative minds, and is well based on a foundation of hard work in the study of facts and first principles. Vegetable Physiology has likewise made remarkable advances, has disencumbered itself of many aseless accumulations, and has achieved much that is of direct bearing on the art of cultivation. The author has endeavored in this work to lay out a groundwork of facts sufficiently complete to reflect a true and well-proportioned image of the nature and needs of the plant, and to serve the student of agriculture for thoroughly preparing himself to comprehend the whole |