the agent which had transformed common Phosphate of Lime into
a soluble Bi-Phosphate or Superphosphate.

The analysis mentions 1.8 per cent. of Soluble Phosphoric
Acid; this cannot be attributed to the action of Sulphuric Acid
on the original Phosphates. Nobody need however be astonished
at its presence who knows the action of Ammoniacal Salts on
Phosphates. Ammoniacal Salts, especially Sulphate of Ammo-
nia, dissolve pretty readily Phosphate of Lime, and to this fact
the great effect of Peruvian Guano must to some extent be attrib-
uted. Peruvian Guano, as we know, contains Phosphate of
Lime besides Ammonia; if this article is mixed with Sulphate of
Lime (Plaster of Paris) or applied to a soil which contains origi-
nally Plaster of Paris, Sulphate of Ammonia is formed, which
acts as a solvent to the Phosphate of Lime. We even know by
experiments made with mixtures of Peruvian Guano and Mexi-
can, (pure Phosphate of Lime,) that the Sulphate of Ammonia
which is formed from 100 lbs. of Peruvian Guano makes availa-
ble not only the Phosphate of Lime which these 100 lbs. contain,
but that it acts also on additional qualities of Phosphate of Lime,
which the Mexican Guano contained, and that for this reason the
application of a mixture of Peruvian Guano and Mexican is in
all cases far more economical and rational than the application of
Peruvian Guano alone, provided that the soil is deficient in Phos-
phoric Acid.                         

Dr. Stewart shows Ammoniacal Salts to be present in C. B.
DeBurg's Super Phosphate of Lime, and the presence of 1.8 per
cent, of Soluble Phosphoric Acid must therefore be the conse-
quence of the action of these Ammoniacal Salts on Phosphates;
the absence of Sulphuric Acid, or any other stronger acid than
Phosphoric, excludes every other reason for its presence. But if
this is the case, (and no other case is possible from the analysis,)
we will at once perceive a great mistake as to the valuation of
the article. The value of the Ammoniacal Salts contained in the
article is first estimated, then the value of its Phosphates, and
finally the value of the Soluble Phosphoric Acid, which estimated
to be equivalent to five times the proportion of Bone Phosphate
of Lime that it represents. By these means the analyst estimates
first the agents, which are Ammoniacal Salts and Phosphates, and
secondly their reciprocal effect which produced Soluble Phospho-
ric Acid. Such a valuation is, however, totally wrong and liable
to mislead farmers and Purchasers of this article. A hotel keeper
who would charge for the beef and for roasting it, and finally for
the resulting roast beef, would act on the same principle as that
by which the money value of this article is estimated.

If I make "the most liberal allowance," as Dr. S. did in esti-
mating the money value of this "fertilizer," allowing $25 for

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