On Phosphatic Guanoa. 
443 
2n(l. Deposits which, like Ichaboe, Saldanha Bay, Bolivian, 
Chilian, and Upper Peruvian guanos, have lost a more or less 
considerable portion of their nitrogenous soluble saline con- 
stituents. The guanos belonging to this class generally contain 
from 2 to 4 per cent, of ammonia. 
3rd. Guanos which have lost nearly all their nitrogenous con- 
stituents, and consist principally of the earthy phosphates of 
the animal deposit, and some organic matter which has resisted 
the solvent action of the water which converted the original 
deposits into phosphatic guanos. 
Many of the latter are contaminated with fine sand, and some 
also with carbonate and sulphate of lime. 
It is not my purpose in this paper to treat of the two former 
classes, and I shall confine myself to the chemical history of 
phosphatic guanos. This contribution to the pages of our 
'Joui'nal' I trust will form a useful, although perhaps not very 
interesting, sequel to my paper on " Phosphatic Minerals used 
in Agriculture," published in a preceding volume of the 'Journal,' 
and complete the account of the great variety of phosphatic 
materials which at the present time are placed at the command 
of manufacturers of artificial manures, and in one shape or other 
are made subservient to the needs of British agriculture. 
Phosphatic Guanos. 
Phosphatic guanos, as stated already, are produced when 
water acts upon deposits of birds -dung to such an extent that 
nearly the whole of the nitrogenous organic constituents of the 
dung are converted into soluble salts of ammonia, which, 
together with the soluble saline matters, are washed away, and 
little else but the phosphates of lime and magnesia of the original 
animal deposits, more or less pure, are left behind. All true 
phosphatic guanos contain some organic matter, and with it at 
least traces of nitrogen. JNIost kinds yield from one-third to 
one-half per cent, of nitrogen, and some as much as three-fourths 
to one per cent. Ammoniacal salts, as a rule, are absent, or pre- 
sent only to a limited extent. However, there is no distinct 
line of demarcation which separates phosphatic from ammo- 
niacal guanos, and some may be described under one head with 
as much propriety as under the other. 
• Our principal supplies of phosphatic guanos come from South 
America, South Africa, a number of islands in the Caribbean 
or West Indian Sea, and several uninhabited islands in the 
South Pacific. From these places we obtain the following 
