444 
On Phosphatic Guanos. 
varieties, whicli have from time to time been brought under mv 
notice : — 
1. Mejilloncs Guano. 
2. Patagoniaa and Falkland Island 
Guano. 
3. Patos Island Guano. 
4. Eaza Island, or Gulf of California 
Guano. 
5. Curafao Guano. ■ 
6. Quito Serrano Island Guano. 
7. Petrel Island Guano. 
8. Coral Island Guauo. 
9. Booby Island Guano. 
10. McKccn's Island Guano. 
11. Baker Island Guano. 
12. Howland Island Guano. 
13. Jar\as Island (niano. 
14. Birds' Island Guauo. 
15. Maiden Island Guano. 
16. Siiaw's Island Guano. 
17. Flint Island Guano. 
18. Enderbury Guano. 
19. Starbuck Island Guano. 
Besides these varieties, others have been examined by me, but 
as I have not been able to trace their origin, I pass them over 
and confine my remarks to the preceding kinds. 
Mcjillones Guano. — Although it has long been known that 
guano-deposits of great extent exist in the high table-land near 
the coasts of Bolivia, between Peru and Chili, a little below 
the tropic of Capricorn, it is only during the last few years that 
these deposits have been systematically explored. At the present 
time a good many cargoes of one of the most valuable phos- 
phatic guanos are annually shipped to England from Mejilloncs 
Bay, which is but a short distance from the principal guano- 
deposits, situated about 1700 feet above the sea, towards the 
base of the Marro de Mejilloncs, a mountain 2600 feet high. 
This deposit is of great extent, and varies in depth from 5 to 
20 feet, and in some places reaches a depth of 40 feet. A 
second deposit, not yet fully explored, occurs at La Tetas, north 
of the principal one. The quantity of available guano is 
variously estimated by the engineers who have surveyed ths 
deposits. According to official statements there are from 
2,000,000 to 4,000,000 tons, thus showing a wide margin in 
the estimates. It is next to impossible to form a correct esti- 
mate of almost any guano-deposits, but there appears to be n© 
reasonable doubt that some millions of tons may be expected 
from Mejilloncs. 
Mejilloncs guano has a bright-reddish colour, very similar to 
the colour of red ochre. The colour, however, I find is hot due, as 
might be supposed, to red oxide of iron, but to a peculiar organic 
colouring matter, which turns much lighter and assumes a 
yellowish tint when the guano is hard dried. 
About three-fourths of the bulk consists of fine powder, and 
the remainder of small lumps, which are readily crushed. The 
guano has a low specific gravity, and when mixed with water the 
greater part remains in suspension for a long time, showing 
