208 Composition and Value of Guano. 



proportion in the different specimens is of the highest importance. 

 In the 32 specimens from which the preceding averages have 

 been drawn, we find — 



The lowest proportion (Spec, 33) . is . 15*98 per cent. 

 The highest ,, (Specimens 1 and 45) . 18*94 „ 

 The average of 32 specimens being . . 17"41 „ 



That the above per centage of ammonia is higher than most 

 persons have been in the habit of considering it, I think will be 

 readily granted. The great number of specimens examined, and 

 the period of time during which they have been collected, are 

 however greatly in favour of an uniformity in the composition of 

 true"^ Peruvian guano. The character of the guano islands 

 themselves is also an additional argument on the same side. I 

 am informed by a gentleman, who for several years has person- 

 ally superintended the loading of the guano ships, that the island 

 from which the Peruvian guano is brought, and which is one of a 

 group called the Chincha Islands, is one mass of the manure, having 

 a circumference of 5 or 6 miles. 



At the point where the guano is now worked, the height of the 

 deposit is upwards of 80 feet, and the removal of some 200,000 

 tons has scarcely affected it in a perceptible degree. As may be 

 imagined from the immense weight of the mass, and the gradual 

 way in which it has been formed, its solidity is very considerable, 

 and in some cases it has been necessary to blast it as we would a 

 rock of sandstone or limestone. It will be obvious that in such 

 circumstances the guano would be preserved with little loss. 

 Leaving the further consideration of ordinary Peruvian guano, 

 until we are in a position to enter upon the question of money 

 value, I now pass on to the other known varieties. 



There is a variety of guano, of which a few cargoes only have 

 reached England, and which is known in Peru as Angamos 

 guano. It is in no way peculiar, except in being above the aver- 

 age richness in ammonia, and somewhat whiter in colour. It is 

 a deposit of recent formation, being collected by hand, and at 

 considerable expense, from the rocks wdiich the birds frequent — 

 not more than 400 or 500 are annually obtainable. 



The following Table exhibits the composition of 4 specimens 

 of this kind of guano : — 



* I say true Peruvian guano, because other varieties, such as the Bolivian and 

 Chilian, are brought from the same part of the world. I have not yet had an oppor- 

 tunity of examining specimens of these kinds of guano, and am not therefore in a po- 

 sition to say whether they are of the same value and exhibit the same uniformity in 

 composition as those above described. The importers are expecting cargoes of Boli- 

 vian guano during the present summer (1849), and have promised to supply specimens 

 for analysis, upon whicli I shall hope to report in a future Journal. 



