to the free use which has been made
throughout the book of the results of these experiments, the last
chapter contains, in a tabular form, a short epitome of some of the more
important Rothamsted researches on the action of different manures.

To the numerous German and French works on the subject, more especially
to Professor Heiden's encyclopaedic 'Lehrbuch der Duengerlehre' and the
various writings of Dr Emil von Wolff, the author is further much
indebted.

Among English works he would especially mention the assistance he has
derived from the writings of Mr R. Warington, F.R.S., Professor S. W.
Johnson, Professor Armsby, the late Dr Augustus Voelcker, and others. He
would also tender his acknowledgments to the new edition of Stephens'
'Book of the Farm,' and he has to thank its editor, his friend Mr James
Macdonald, Secretary to the Highland and Agricultural Society of
Scotland, for having read parts of his proof-sheets.

It is also his pleasing duty to thank his friends Dr Bernard Dyer, Hon
Secretary of the Society of Public Analysts, Dr A. P. Aitken, Chemist to
the Highland and Agricultural Society of Scotland; Professor Douglas
Gilchrist of Bangor; Mr F. J. Cooke, late of Flitcham; Mr Hermann Voss
of London; and Professor Wright of Glasgow, for having assisted him in
the revision of proof-sheets.

ANALYTICAL LABORATORY,
128 WELLINGTON STREET, GLASGOW,
_January_ 1894.

CONTENTS.

PART I.--HISTORICAL INTRODUCTION.
PAGE
Beginning of agricultural chemistry 4
Early theories regarding plant-growth 4
Van Helmont 4
Digby 6
Duhamel and Stephen Hales 8
Jethro Tull 9
Charles Bonnet's discovery of source of plants' carbon 11
Researches of Priestley, Ingenhousz, Senebier, on assimilation
of carbon 11-12
Publication of first English treatise by Earl Dundonald 13
Publication of Theodore de Saussure, 'Chemical Researches on
Vegetation,' 1804 14
Theories on source of plant-nitrogen