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233 THE CHEMISTRY OF SOILS AUB MANURES. 
tJ Without entering into the various speculations offered as to the cause of the many failiu-es in the ^ 
attempts made to cultivate this plant — for -which, indeed, we have not space — we may venture briefly 
to express cm- own conviction that success has not been the result of any one condition applied with 
more than ordinaiy skill ; and, therefore, is not to be traced, specially, either to uninterrupted brio-ht 
light, or the pm-ity of the water as influenced by chai-red soU ; but, rather, has been the rewai'd of a 
skilful eombiuation of the conditions wliieh represent ai-tificially the tropical climate and peculiar 
cii-cunistances which the plant naturally enjoys. These conditions are, in brief: light, clear and £i-ee ; 
water, pui-e and constantly changing ; heat, steady and powerful, though not excessive, in respect both 
to the water and the atmosphere — all these combined and acting iu concert. — M. 
TPIE CHEMISTRY OF SOILS ASB MANURES. 
By Dii. A. YOELCKEK, Pkofessor of Chemistry ix the Eoyal Ageiculturai. College, CmENCEsiEii. 
I.VTRODUCTOET. 
1?T10 the peculiai'ities of the present time belong the rapid progress of natural science, the striking 
ix and important discoveries -with which the labom-s of some of the most accomplished natural 
philosophers have been rewai'ded, the high esteem in which the study of natui'e is held by the 
public at lai'ge, and the general dcsii'e for information which makes itself felt in places where, 
hitherto, the rays of the Ught of science faUed to penetrate. The spirit to reform and revolutionize, 
till now confined to reUgion and politics only, no longer regards these topics as its own exclusively, 
but extends its mighty influence over an extensive range of subjects, and is manifesting itself likewise 
in producing those changes in the system of education, which have tended greatly to secure to 
natm'al science a place in the affections of all classes of society, which it did not possess twenty yeai-s 
ago. Indeed, no man of sound judgment will regard instruction in natural history and philosophy 
supei-fluous in a system of liberal education, and many professional men — the physician, the artist, 
the manufacturer, &c. — will fail to be successful in theii- different callings, if they be ignorant of the 
piinciples of natui-al science. A sure safeguai'd against iniiu in these times of competition is increased 
knowledge ; for knowledge is power, and certain to benefit its possessor. 
Can we then feel sm-pi-iscd when we see an intelligent manufactm-er, fai'mer, or gardener, who has 
paid some attention to the study of natui-al science, succeed in his undertakings, whilst many, who 
have not paid that attention, fail ? On the contrary, what sui-prises us is, that this truth is not 
universally admitted, or, we should rather say, is too frequently forgotten ; for we do not conceive 
how any one who has given a moment's thought to this subject, can hesitate to admit the fact that 
the artist, manufactui-er, or gardener, who is acquainted with the principles of natm-al science, so 
far as to understand the natm'e of the suggestions made fi'om time to time by the man of science, and 
to reduce them into practice, or to call into hfe new improvements, possesses considerable advantages 
over othei's who lack this kind of knowledge — advantages which will secui'e him almost certain 
success in entering into competition with the latter. It is just the usefulness, the extensive apphcation, 
which can be made of any branch of natural science, and the material benefits already derived from 
the labom-s of the chemist, botanist, and geologist, which has contributed more than anything else to 
the greater appreciation of natm-al science. The peculiar feature of most of the recent discoveries 
made iu chemistry is, that they are all, more or less, chai-acterized by a practical tendency ; hence 
the extensive and general apphcation which chemisti-y finds in the various occupations iu which man 
is engaged, and the high esteem in which this branch of science is held by practical men. Though 
chemistry, in common with anj' branch of natural study, will afford real and lasting pleasure to the 
student, and tend to sharpen his powers of observation and judgment ; it is, nevertheless, chiefly on 
account of its practical utility, that it is now more extensively taught, and better appreciated by the 
student than formerly. The practical utility of chemical knowledge will become apparent, if we bear 
in mind the objects of chemistry, which are to inquire into the natm-e of all material substances, to 
determine accurately theu- compositions, to ascertain minutely the properties of aU substances which 
enter into the composition of the rocks which form the sohd part of the earth, of the water in which 
the latter may be said to be immersed, of the air by which the earth is sun-ounded, of the plants 
which vegetate, and animals which breath upon it ; to study the changes which are continually going 
on in nature, to point out the laws which govern the same, and to determine the cir-cumstances which Ih, 
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