Vermont watchman and State journal. [volume] (Montpelier, Vt.) 1836-1883, 1881-04-27
Adhesion OF Another Chemist.

Chemical Professor u. Z. Caldwell gives
in qualified adhesion to our views in re-
gard to phosphate fertilizers, in the Rural
New Yorker, as follows; Dr. Hoskns ques-
tions the reliability, at least for practical
purposes, of the comparative trade valuation
generally adopted in this country of phos-
phoric acid in the three forms of phosphate
He thinks that reverted acid is quite as val
liable as soluble acid; that bone ash, finely
ground, is nearly as effective as soluble phos-
phate, and that South Carolina phosphate
may be, if ground fine enough, nearly equal
to bone ash. should say that he may be
correct, in respect to part of these PROPOSE
tions, and that he may not. In France and
Belgium, soluble and reverted acid are, it is
true, held to be equal in value, for reasons
based partly on the results of pot and field
culture experiments, and no distinction is
made between them in the analysis and val
uation Of a commercial fertilizer. But this
view does not prevail elsewhere in Europe.
The relative value of the two forms OF the
acid has recently been made the subject of
GUS, in Germany. 1t appears from these
discussions to be established that on sandy
or peaty soils, poor in lime, the reverted acid
may be fully as effective as the soluble acid,
and in some cases it has even given better
return. 1t is supposed that in such cases
the soluble acid, meeting no lime with the
aid of which it can pass back into diff
Guilty soluble state and remain fixed in the
soil and within reach Of the plants during
the seasons growth, is really leached out OF
the soil before the crops can get hold of a
sufficient quantity of it to affect the yield to
any considerable extent. On the other hand,
experiment has shown better result also
on soil quite rich in lime with reverted
acid than with soluble acid. In this case it
was explained that the soluble acid, when
taken into solution in the soil in the pres
ence OF such an excess of lime, passed quite
back into the original condition in which it
existed when first treated with oil of vitriol
to convert the common phosphate into super
phosphate; but the reverted acid applied to
the soil, occupying an intermediate position
as to solubility, remained in that condition
in the soil, accessible to the plant, yet not so
soluble as to be wasted"
Mercker, one Of the most prominent of
German agricultural chemists, while grant
ing the validity of these conclusions as to
the effect of reverted acid OIL soils either
very poor or very rich in lime, affirms that,
with respect to the large majority Of soils
on which superphosphates are used, we do
not yet know what the comparative value
of reverted acid is for producing crops and
the general feeling in Germany is that more
experiments are needed to establish the con-
clusion which the French and Belgian
chemists have already adopted. Professor
Caldwell (after admitting that American
chemists have contributed nothing to the So
luton Of this question: goes on to say for
himself; 81 am hardly ready, in the face
of the widely prevailing opinion in favor of
soluble phosphate, to acknowledge that far
mers should everywhere, on all kinds of
soils, be as well satisfied with reverted acid
as with soluble acid, when they are so stu
ated that they can be sure of getting as
good superphosphates as they ought to re-
ceive for the prices paid" The professor
proposes, at another time, TO notice the pres
ent condition of the no less important ques-
tion concerning the use Of bone-meal, bone
ash, or mineral phosphate in place of su-
perphosphate. We shall read what he has
to say with interest, but it is curious to
note that in these matters the chemists in all
countries are following, rather than leading,
the intelligent practical farmers in their
conclusions.