manures well worth the
money asked for them.

"A correct analysis," said I, "furnishes the only sure test of value.
'Testimonials' from farmers and others are pre-eminently unreliable.
With over thirty years' experience in the use of these fertilizers,
I would place far more confidence on a good and reliable analysis than
on any actual trial I could make in the field. Testimonials to a patent
fertilizer are about as reliable as testimonials to a patent-medicine.
In buying a manure, we want to know what it contains, and the condition
of the constituents."

In 1877, Prof. S. W. Johnson gives the following figures, showing "the
trade-values, or cost in market, per pound, of the ordinary occurring
forms of nitrogen, phosphoric acid, and potash, as recently found in the
New York and New England markets:
_Cents
per pound._
Nitrogen in ammonia and nitrates 24
" in Peruvian Guano, fine steamed bone, dried
and fine ground blood, meat, and fish 20
" in fine ground bone, horn, and wool-dust 18
" in coarse bone, horn-shavings, and fish-scrap 15
Phosphoric acid soluble in water 12-1/2
" " "reverted," and in Peruvian Guano 9
" " insoluble, in fine bone and fish guano 7
" " " in coarse bone, bone-ash,
and bone-black 5
" " " in fine ground rock phosphate 3-1/2
Potash in high-grade sulphate 9
" in kainit, as sulphate 7-1/2
" in muriate, or potassium chloride 6

"These 'estimated values,'" says Prof. Johnson, "are not fixed, but vary
with the state of the market, and are from time to time subject to
revision. They are not exact to the cent or its fractions, because the
same article sells cheaper at commercial or manufacturing centers than
in country towns, cheaper in large lots than in small, cheaper for cash
than on time. These values are high enough to do no injustice to the
dealer, and accurate enough to serve the object of the consumer.

"By multiplying the per cent of Nitrogen, etc., by the trade-value per
pound, and then by 20, we get the value per ton of the several
ingredients, and