GUANO. 173 



frauds of this description, if he will only take the 

 trouble to institute a few simple tests, such as are 

 specified at the conclusion of this chapter. 



1. Sources and Constituents of Guano. 



Guano is composed of the excrements of sea-birds, 

 which have accumulated in the lapse of time, in lay- 

 ers of greater or less depth, upon uninhabited isl- 

 ands and cliffs. Good guano comes to us from those 

 zones of the earth in which it never, or at least ex- 

 tremely seldom, rains, and from such islands as are 

 sufficiently elevated to prevent the overflowing of 

 sea-water ; for if either happened, the best and most 

 efficacious portions of the guano would be dissolved 

 and washed away. If a dung-heap is suffered to 

 lie without attention for only a few years, with the 

 sun shining upon it, the air driving through it, and 

 the rain washing it away, what will at last be left of 

 it ? Not much beyond a few earthy or mineral sub- 

 stances, which could not be dissolved or volatilized. 

 Such washed-out and worthless guano is very often 

 found in commerce, and against it the farmer must 

 be upon his guard. Amongst these are the cargoes 

 which come to us from Chili and Patagonia, since 

 these countries are inundated with heavy rains. In 

 like manner, those kinds of guano now met with un- 

 der the name of " African " must be enumerated 

 here ; whereas the guano brought two or three years 

 since from Africa, which bore the name of " Ichaboe 

 15* 



