C 264 3 



kind. It exists abundantly, as \ve are informed by 

 M. Humboldt, on the small islands in the south sea, 

 at Chinche, Ilo, Iza, and Arica. 50 vessels are la- 

 den with it annually at Chinche, each of which carries 

 from 1500 to 2000 cubical feet. It is used a manure- 

 only in very small quantities ; and particularly for 

 crops of maize. I made some experiments on speci- 

 mens of guano sent from South America to the Board 

 of Agriculture in 1 805. It appeared as a fine brown 

 powder ; it blackened by heat, and gave off strong 

 ammoniacal fumes ; treated with nitric acid it afford- 

 ed uric acid. In 1806 M. M. Fourcroy and Vauque- 

 lin published an elaborate analysis of guano. They 

 state that it contains a fourth part of its weight of uric 

 acid, partly saturated with, ammonia, and partly with 

 potassa ; some phosphoric acid combined with the 

 same bases, and likewise with lime. Small quantities 

 of sulphate and muriate of potassa. a little fatty matter, 

 and some quartzose sand. 



It is easy to explain its fertilizing properties : 

 from its composition it might be supposed to be a very 

 powerful manure. It requires water for the solution 

 of its soluble matter to enable it to produce its full 

 beneficial effect on crops. 



The dung of sea birds has, I believe, never been 

 used as a manure in this country ; but it is probable, 

 that even the soil of the small islands on our coast 

 much frequented by them, would fertilize. Some 

 dung of sea birds brought from a rock on the coast of 

 Merionethshire, produced a powerful but transient 

 effect on grass. It was tried, at my request, by Sir 

 Robert Vaughan at Nannau. 



