---------------+-------------------+
| |100.00 ...100.00 |100.00 ...100.00 |
| Ammonia, | 0.11 ... 0.57 | 1.28 ... 1.55 |
+-----------------------------------+-------------------+-------------------+

Superphosphates made from bones alone are generally distinguished by a
large quantity of ammonia, and a rather low per centage of biphosphate
of lime. This is owing to the difficulty experienced in making the acid
react in a satisfactory manner on bones, the phosphates being protected
from its action by the large quantity of animal matter which, when
moistened, swells up, fills the pores, and prevents the ready access of
the acid to the interior of the fragments. Superphosphates from
bone-ash, on the other hand, contain a mere trifle of ammonia, and when
well made a very large quantity of biphosphate of lime. Their quality
differs very greatly, and depends, of course, on that of the bone-ash
employed, which can rarely be obtained of quality sufficient to yield
more than 30 or 35 per cent of soluble phosphates. Coprolites are seldom
used alone for the manufacture of superphosphates, but are generally
mixed with bone-ash and bone dust. Mixtures containing salts of ammonia,
flesh, blood, etc., are also largely manufactured, and some are now
produced containing as much as four or five per cent of ammonia, and the
consumption of such articles is largely increasing.

The analyses above given are all those of good superphosphates, in which
abundance of acid has been used so as to convert a large proportion of
insoluble into soluble phosphates; but there are many samples of very
inferior quality to be met with in the market, in which the proportion
of acid has been reduced, and the quantity of phosphates made soluble is
consequently much lower than it ought to be. The following analyses
illustrate the composition of such manures, which are all very inferior
and generally worth much less than the price asked for them.

Water 21.60 5.37 7.19
Organic matter and ammoniacal
salts, 11.62 13.91 8.80
Biphosphate of lime 2.98 2.02 6.42
Equivalent to soluble
phosphates (4.65) (3.15) (10.02)
Insoluble phosphates 25.70 15.80 14.03
Sulphate of lime