1882.] COMMERCIAL FERTILIZERS. 63 



Notice first the geographical position and origin of the deposits. 

 They lie on the western coast of South America, chiefly in Peru, 

 but in small amount in Chili, and Bolivia also. Not far to the 

 east of them rises the great mountain system of the Andes, with 

 its several lines of ridges and spurs standing guard over the most 

 extensive and valuable store of chemical treasure in the world. 



In the region where these treasures lie, the wind blows from the 

 east and southeast uninterruptedly through the year, and the pro- 

 tecting mountains dry these winds completely. As the current, 

 loaded with moisture from the Brazilian forests, strikes the eastern 

 spurs of the Andes, it cieposits most of its burden in heavy rains. 

 As it climbs the higher ranges it is cooled still more, and when it 

 passes the snow-capped summits the last traces of water are 

 wrung from it, and it sweeps down over the plains of Peru, drink- 

 ing up their water and making thenr, except by the water courses, 

 a barren desert. 



Rain therefore is almost unknown there, at least between lati- 

 tudes 14° and 21° S. At Iquique rain falls in a light shower once 

 in many years. In other places the fall of rain is as much of an 

 histoi'ical event as the "Dark Day "was in New England. ,In 

 such a country, and in such alone, can guano deposits be formed 

 or remain ; for from one-half to three-fifths of Peruvian guano is 

 very soluble in rain water. Deposits are found in various places, 

 but the most remarkable are the Chincha islands, which lie in the 

 Pacific, not far from the coast. The islands are of granite, abso- 

 lutely barren, and when first worked for the export trade were 

 covered in places over 100 feet deep with guano, while in other 

 places the deposit was not over four feet deep. It is entirely free 

 from any admixture of earth. This guano consists mainly of the 

 excrement of birds, together with their feathers and carcases, and 

 has been accumulating for centuries. 



Enormous flocks of birds, chiefly gulls, pelicans, cormorant, and 

 gannet live on the coast, and these islands serve for t>feeir homes, 

 their breeding places, and their cemeteries. 



The waters about there teem with fish of various sorts. The 

 stories told of their numbers are too fishy to be rehearsed, but we 

 may well believe that the actual facts are something of which we 

 can have small conception, aiid fish furnish all the food of the 

 birds. What makes the excrement of birds particularly valuable 

 as a fertilizer, is that the excretion of both kidney and intestines 

 is mixed in the cloaca, and voided in a comparatively solid condi- 



