Kneeland.] 236 [April 16, 
1819, until 1840; since that time it has been exported from the 
Peruvian islands in very large quantity. 
The three small islands off the south coast of Peru, called the 
Chincha islands were believed to contain at least forty million tons, 
the deposit being in some places more than one hundred and sixty : 
feet thick. The demand for it was so great that search was made 
for other sources of supply, all of which, however, proved inferior to 
the Peruvian. : 
The reason of the superiority of the latter is, that no rain falls on 
these islands, and the ingredients are little changed under their dry 
tropical sun; the uric acid and ammonia, both readily decomposing 
under the influence of moisture, remain unchanged and dry. Where 
rain prevails, these nitrogenous compounds are washed out, and the 
value of the guano then consists in the amount of the phosphates 
which remain —this last, or the phosphatic guano, is the one of 
which I wish to speak to-night. 
The differences will be made more plain by a glance at the follow- 
ing analyses: 
Peruvian. Jarvis Island. Baker’s Island. 
Water : . 12 to 20 per cent. 7.5 per cent. _ 4.5 per cent. 
Organic Matter and 
ce 4 14 THI 6c 
Ammoniacal Salts 
Soluble Salts Gita ge 7.5 7 H 
Phosphate Lime 17 to22 “ 81 e 76 . 
98 100 5 9B 5 
By Dr. Draper, of N. Y. 
The difference in the ammoniacal salts and organic matters which 
have been washed out in the last two, or rainy islands, and the pre- 
dominance of the phosphates in these last, to which these specimens 
belong, will be noticed. 
The difference in these guanos is of great importance in their agri- 
cultural applications, as it will be readily seen that the rich ammo- 
niacal guanos of Peru would be of little use in light soils, where 
volatile and soluble parts would easily be lost by being washed out, 
while the insoluble phosphatic varieties would be better and cheaper. © 
Jarvis, Baker’s and Howland’s islands, nearly on the equator, in the 
Pacific, between 159° and 176° W. long, and a few others in the 
neighborhood, belonging to the American Guano Company, are quite 
valuable, containing about ten million tons, and have largely supplied 
the American market. The island from which these specimens came, 
