452 
On Pliosphatic Guanos. 
Like most phosphatic guanos the deposit varies a good deal 
in different places on the island ; but when care is taken in the 
selection of the different qualities, cargoes yielding from 67 to 
70 per cent, and upwards of phosphate of lime may be shipped 
without much difficulty. The analyses on the preceding page 
give a good representation of the variation in the quality of 
this guano. 
Curaqao guano thus contains scarcely any siliceous matter, 
from 64 to 73 per cent, of phosphate of lime, and a variable 
moderate percentage of carbonate of lime. 
Quite recently a very rich rock phosphate has been discovered 
on Great Curacao. A sample analysed by me a few months ago 
had the following composition : — 
Composition of a Sample of Curarao Hock-pliospliate. 
MoistiTve 1 • 34 
Organic matter "Si 
*PLiospboric acid 37 '53 
Lime 51 "SO 
fCarbonic acid 4 • 28 
Magnesia, sulphuric acid, &:c 3*87 
Insoluble siliceous matter '34 
100-00 
* Equal to tribasic phosphate of lime .. 81 "OS 
f t Equal to carbonate of lime 9 • 72 
This is a hard light-coloured rock, well adapted for the 
manufacture of concentrated mineral superphosphate. 
In the next tabular statement (p. 453) are grouped together 
analyses of samples of Quito Serrano guano, Petrel Island guano. 
Coral Island guano, Booby Island guano, and INIcKeen Island 
guano, varieties of phosphatic guanos which are occasionally 
imported into England, but which do not appear to form very 
extensive deposits. 
The sample of Coral Island guano analysed hy me, it will be 
seen, contained 77 per cent, of phosphate of lime, which is a 
high percentage ; but the Booby Island and jNIcKeen Island 
guanos are not rich enough to repay the expenses of exportation. 
Baker Island Guano. — Baker Island, a small ui^inliabited 
coral island, surrounded by coral reefs, is situated in the West 
Indian, or Caribbean Sea, at an elevation of about 25 feet above 
the level of the sea. It is the resort and breeding-place of great 
numbers of sea-birds, the excrements of which give rise to the 
guano deposit. Unfortunately the island is visited periodically 
by heavy rains, which deprive the l^irds'-dung of its most 
valuable fertilizing constituents, and leave mainly the earthy 
phosphates, mixed with more or less organic matter, behind. 
