On Pliospliatic Guanos. 453 
Composition of Samples op: — 
Quito 
Serrano 
Island 
Guano. 
Petrel 
Island 
Guano. 
Coral 
Island 
Guano. 
Booby 
Island 
Guano. 
McKcon 
Island 
Guano. 
Magnesia, sulpliiiric acid, j 
lasoluble siliceous matter 
8-50 
32-44 
39-41 
17-10 
2- 55 
9-5l| 
30-50 
36-44 
18-05 
5-50 
7-04 
11-76 
35-29 
41-76 
3-55 
■CO 
6-10 
10-18 
21-77 
45-36 
16-50 
-09 
12-55 
9-59 
22-68 
36-24 
18-15 
-79 
100-00 
100-00 
100-00 
100-00 
100-00 
* Equal to tribasic pliosphatel 
f Contaiaing nitrogen . . . . "I 
Equal to ammonia . . . . / 
70-82 
66-58 
•• { 
77-05 
-38 
•46 
47-52 
} ■■ 
49-56 
/ -26 
\ -32 
The surface layer of the guano is powdery and of a brown 
colour, and exhibits numerous fibres of roots and similar vege- 
table remains. In the lower layers are found a good many 
lumps, varying in hardness, size, and texture. The strata 
resting immediately upon the coral-rock are somewhat crystal- 
line, and contain from 20 to 25 per cent, of sulphate of lime. 
If worked too near the rock, the guano is liable to get con- 
taminated with carbonate of lime, of which substance the coral 
rocks almost entirely consist. 
The chemical character of Baker Island guano will be 
readily recognised by the following analyses, made in my labo- 
ratory a few years ago : — 
Composition of Baker Island Guano. 
Moisture 
*Organio matter 
tPhosphoric acid 
Lime 
JCarbonic acid 
Magnesia 
Oxide of iron 
Alumina 
Sulphuric asid 
Alkalies, and loss in analysis 
Insoluble siliceous matter 
* Containing nitrogen 
Equal to ammonia 
t Equal to tribasic phosphate of lime 
X Equal to carbonate of lime 
Ko. 1. 
12-05 
6-25 
32-32 
42-34 
2-99 
-71 
•141 
•m 
1-19) 
1-78 
•14 
100-00 
70^55 
6-79 
No. 
4' 
6' 
.S9' 
43' 
71 
17 
44 
01 
27^ 
32 
-96 ' 
•33 
•79 
100 
00 
86 
34 
41 
11 
61 
VOL. XIL — S. S. 
2 II 
