Produced by Steven Giacomelli, Barbara Kosker and the Online Distributed Proofreading Team at https://www.pgdp.net (This file was produced from images produced by Core Historical Literature in Agriculture (CHLA), Cornell University) PRINCIPLES OF MANURING MANURES AND THE PRINCIPLES OF MANURING BY C. M. AIKMAN, M.A., D.Sc., F.R.S.E., F.I.C. FORMERLY PROFESSOR OF CHEMISTRY, GLASGOW VETERINARY COLLEGE, AND EXAMINER IN CHEMISTRY, GLASGOW UNIVERSITY; AUTHOR OF 'FARMYARD MANURE,' ETC. THIRD IMPRESSION WILLIAM BLACKWOOD AND SONS EDINBURGH AND LONDON MCMX D. VAN NOSTRAND COMPANY NEW YORK _All Rights reserved_ TO SIR JOHN BENNET LAWES, BART., D.C.L., LL.D., F.R.S., OF ROTHAMSTED, AND SIR J. HENRY GILBERT, M.A., LL.D., F.R.S., FORMERLY SIBTHORPIAN PROFESSOR OF RURAL ECONOMY, UNIVERSITY OF OXFORD, WHOSE FAMOUS INVESTIGATIONS DURING THE LAST FIFTY YEARS HAVE SO LARGELY CONTRIBUTED TO BUILD UP THE SCIENCE OF MANURING, THIS WORK, EMBODYING MANY OF THE ROTHAMSTED RESULTS, IS DEDICATED. PREFACE. When the present work was first undertaken there were but few works in English dealing with its subject-matter, and hardly any which dealt with the question of Manuring at any length. During the last few years, however, owing to the greatly increased interest taken in agricultural education, the demand for agricultural scientific literature has called into existence quite a number of new works. Despite this fact, the author ventures to believe that the gap which the present treatise was originally designed to fill is still unfilled. Of the importance of the subject all interested in agriculture are well aware. It is no exaggeration to say that the introduction of the practice of artificial manuring has revolutionised modern husbandry. Indeed, without the aid of artificial manures, arable farming, as at present carried out, would be impossible. Fifty years ago the practice may be said to have been unknown; yet so widespread has it now become, that at the present time the capital invested in the manure trade in this country alone amounts to millions sterling. It need scarcely be pointed out, therefore, that a practice in which such vast monetary interests are involved is worthy of the most careful consideration by all students of agricultural science, as well as, it may be added, by political economists.