THE CHEMISTRY OF SOUS AND MANUEES. 
is prosecuted as an advancing art, have undergone, especially tlu-ougli the agency of this rapidly- 
progressing science. But although much has heen done by agricultural chemistry ah'eady, still 
infinitely more remains to be investigated. This new science may be said to be stiU in its infancy ; and 
for that reason it ought not to assume the position of a matured, exact branch of science, like mathe- 
matics, when we are reasoning on detached observed facts connected with the natm-e of soils, and the 
doctrine of manm-es, or the nutrition of plants, as the case may be. How often do we not find 
chemists fall into the error of discussing an isolated fact in natm'e, and explaining its cause with as 
much assurance as if it were in harmony with the whole economy of nature, and the premises on 
which these deductions are founded as infallible as those on which a mathematical problem rests. 
This eiTor, into which some chemists hare fallen, has done a great deal of hann, and given a sudden 
cheek to agricultm-al chemistry in this country ; because practical men, finding the high expectation 
which they were led to entertain by the exaggerated statements of some scientific men, not sub- 
sequently realized, declai-ed themselves deceived, and instead of separating the good gi-ain fi-om the 
bad — well-authenticated facts fi-om exaggerations, mere theories, and wild speculations — have discarded 
at once the aid of a science which is so pre-emioently calculated to benefit the cultivators of the soil. 
"WTio, then, is the more to blame — the practical man, whose previous ideas of chemistry did not allow 
him to form a right estimate of an exaggerated statement, or the scientific, or would-be scientific man, 
who is aware of his exaggerations, or ought to be acquainted ^vith the real merits of the case, before 
he went forward as a teacher of others ? Ought we to condemn this branch of natural science itself 
as useless or unprofitable, because administered by an rminformed or inexperienced empyric ? SiU'ely 
not : the blame rests on such professors, who, with a smattering of knowledge, combine a total dis- 
regard for practical experience ; and with all the conceit and presumption of a charlatan, either out 
of self-esteem, or for the sake of selfish purposes, bombastically proclaim the new doctrine to the 
unsuspecting public. Chaidatans, wild enthusiasts, and amateuring dilettants, may attract attention 
for a short time, but we inay rest assm-ed, sooner or later, they will bring down upon themselves 
disgrace, and discredit on the science which they profess. 
True scientific knowledge on the conti'ary, submitted with modesty and caution, though slow in its 
action upon the mind of the pubUo, convincing in the end, ^vill be regarded as possessing greater value 
than even the most ingenious theories that can be propounded. But how is the practical man to decide 
between truth, established by well authenticated facts, and mere theories, without a knowledge of the 
science and the properties and composition of those substances which come daily under his notice ? 
To the husbandman and the gardener it is a matter of importance to be acquainted with the proper- 
ties of those substances which enter into the composition of the different soils ; the soil is the first 
care of the gai'dener. Upon it he grows plants, the leaves or roots of which serve as food, or the fruits 
of which refi'esh us ; or plants which delight us by the beauty of their flowers and fragrance of their 
scent, or which, as groups of trees and shi-ubs, produce an agreeable impression on the mind of the 
lover of beauty and harmony. All the different kinds of plants are regulated by the soil ; the nature of 
the soil and the gi-owth of plants are, therefore, intimately connected. A knowledge of the composi- 
tion of the different classes of soUs, the relation of their constituent pai'ts to the plants wliich are in- 
tended to be cultivated, will enable the husbandman to change the constitution of the soU by mixing 
together soils of opposite characters, or by adding other less compound substances, in such proportions 
that he shall obtain a mixed soil, or one which shall contain the constituent parts in exactly the relation 
which experience has proved to be most conducive to the production of leaves or flowers, or fruits, or 
to the formation of wood. 
Intimately connected with the chemistry of the soU, is the chemistry of the substances by which 
the fertility of the soil is restored. Without a knowledge of the properties of the materials which 
enter into the composition of the different soils and the requirements of the plants, an improved prac- 
tice of manuring is impossible. The doctrine of the application of manures to the land, ftuther, will 
not be intelligible without a knowledge of the composition of the different manm-es, and the properties 
of the substances upon which their chief fertilizing powers depend, and the cii'cnmstances by which 
the latter may be prcseiwed or increased. "We, therefore, purpose to give, in a series of papers, the 
chemistry of manures, after we shall have lu'st discussed in detail, the origin, composition, physical and 
chemical characters of different classes of soils ; and shall then endeavour to show how the different 
manures may be applied in the most economic and best manner to maintain or to increase the fertiHty 
of any particular soU. 
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