---+-------------------+------------------+------------------+
| | Angamos. | Peruvian. | Bolivian. |
| +---------+---------+---------+--------+---------+--------+
| |Highest. |Lowest. |Highest. |Lowest. |Highest. |Lowest. |
| +---------+---------+---------+--------+---------+--------+
| Water | 12.60 | 7.09 | 10.37 | 21.49 | 11.53 | 16.20 |
| Organic matter } | | | | | | |
| and ammoniacal } | 65.62 | 50.83 | 55.73 | 46.26 | 11.17 | 12.86 |
| salts } | | | | | | |
| Phosphates | 10.83 | 8.70 | 25.20 | 18.93 | 62.99 | 52.95 |
| Alkaline salts | 7.50 | 16.30 | 7.50 | 10.64 | 9.93 | 13.83 |
| Sand | 3.45 | 17.08 | 1.20 | 2.68 | 4.38 | 4.16 |
| +---------+---------+---------+--------+---------+--------+
| | 100.00 | 100.00 | 100.00 |100.00 | 100.00 | 100.00 |
| | | | | | | |
| Ammonia | 25.33 | 17.15 | 18.95 | 14.65 | 1.89 | 2.23 |
+-------------------+---------+---------+---------+--------+---------+--------+

The differences are here exceedingly large; and when the values of the
two Peruvian guanos are calculated according to the method to be
afterwards described, it appears that the highest exceeds the lowest in
value by nearly L3 per ton. Of course, this is an extreme case, but it
is no uncommon occurrence to find a difference of L1 or even L2 per ton
between the values of cargos of Peruvian guano, which are sold at the
same price.

The adulteration of guano is carried on to a very large extent; and
though perhaps not quite so extensively now as it was some years since,
it is only kept in check by the utmost vigilance on the part of the
purchaser. The chief adulterations are a sort of yellow loam very
similar in appearance to guano, sand, gypsum, common salt, and
occasionally also ground coprolites and inferior guano. These substances
are rarely used singly, but are commonly mixed in such proportions as
most closely to imitate the colour and general appearance of the genuine
article. The extent to which the adulteration is carried may be judged
of from the following analyses taken at random from those of a