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question we must invoke the aid of chemistry, and I might add in pass¬ 
ing, that this is the great question in agricultural chemistry which has 
divided the French and German chemists—the head of the latter class 
being Baron Liebig, whose views were for a long time considered as in¬ 
fallible, but the theory of the learned German failed when it was reduced 
to practice. His views were successfully combated by several agricultural 
chemists, both French and English, and the general belief is now against 
him. He endeavored to include agriculture in chemistry, and settle all 
its disputes and regulate its actions by chemical formulae, but Nature re¬ 
sisted the restriction and pursued her own way in spite of the chemioal 
learning of the great Baron. 
Agricultural chemists'are of the opinion that manures are to be classed 
with reference to the nitrogen they contain, or are capable of fixing, and 
by nitrogen in the first instance I include all nitrogenized principles. This 
element, (nitrogen or azote as it is called by the French chemists,) is al¬ 
ways produced by the decomposition of organic matter and may generally 
be detected when the decomposition is rapid by the pungent ammoniacal 
odor ; and the richer the organic substance is in nitrogen, by so much is 
its decomposition more rapid ; the uniformity with which it appears during 
the decomposition of organic matter; and the fact which observation had 
already deduced, that the more highly nitrogenized the substance the 
more valuable it was as a manure, might in itself be sufficient for our 
purpose, but to substantiate more fully this position we will add the 
views of others. 
Boussingault (Rural Economy, p. 254, Appleton’s Ed. 1850, p. 607, 
12mo.) says, “agriculturists have in all ages admitted, that the most 
powerful manures are derived from animal substances, an opinion, or 
rather a fact which, expressed in scientific language, amounts to this— 
that the most active manures are precisely those which contain the larg¬ 
est proportion of azotized principles. It is obvious indeed from every 
thing which precedes, that all the substances which contribute to form 
farm dung, contain azote (nitrogen.) When we consider the immediate 
changes which all highly azotized substances undergo in the process of 
putrefaction, we can foresee that in their transformation into manure they 
must give origin to ammoniacal salts ; and well established facts prove, 
beyond a doubt, that salts having ammonia for their base, must be ranked 
