On the Analysis of Guano. 
289 
phosphates of ammonia, of lime, and of potash and ammonia, with some 
other constituents of little value in agriculture. Klaproth's analysis 
reported 16 per cent, of urate of ammonia, no less than 12 "75 of 
oxalate of lime, 10 of phosphate of lime, 32 of clay and sand, with 
28 '75 of water and indeterminate organic matter. From the great pro- 
portion of clay and sand, Klaproth's sample of guano was obviously not 
genuine. I have met with no specimen of Peruvian guano that con- 
tained any appreciable quantity of clay, and none that contained above 
4 or 5 per cent, of siliceous sand. 
To Mr. Bland, of the firm of Messrs. Myers and Co., I am indebted 
for the following valuable information: — 
The Chincha islands, which afford the best Peruvian guano, are three 
in number, and lie in one line from north to south, about half a mile 
apart. Each island is from 5 to 6 miles in circumference, and consists 
of granite covered with guano in some places to a height of 200 feet, in 
successive horizontal strata, each stratum being from -3 to 10 inches 
thick, and varying in colour from light to dark-brown. No earthy 
matter whatever is mixed with this vast mass of excrement. At Mr. 
Bland's visit to these islands in 1842, he observed a perpendicular sur- 
face of upwards of 100 feet of perfectly uniform aspect from tup to 
bottom. In some parts of these islands, however, the deposit does not 
exceed 3 or 4 feet in thickness. In several places, where the surface of 
the guano is 100 feet or more above the level of the sea, it is strewed 
here and there with masses of granite, h'ke those from the Alpine moun- 
tains, which are met with on the slopes of the Jura chain. These seem 
to indicate an ancient formation for the guano, and terraqueous con- 
vulsions since that period. No such granite masses are found imbedded 
within the guano, but only skeletons of birds. 
The good preservation of the Chincha guano is to be ascribed to the 
absence of rain ; which rarely, if ever, falls between the latitude of 14° 
south, where these islands lie, about 10 miles from the main land, and 
the latitude of Paquica, on the coast of Bolivia, in 21 S. L. By far 
the soundest cargoes of guano which I have analyzed have come from 
Chincha and Bolivia. Beyond these limits of latitude, where rain falls 
in greater or less abundance, the guano is of less value — and what has 
been imported from Chile has been found by me far advanced in decay 
— most of the ammonia and azotized animal substances having been de- 
composed by moisture, and dissipated in the air (by the eremacausis of 
Liebig), leaving phosphate of lime largely to predominate along with 
effete organic matter. The range of the American coast from which the 
guano is taken must therefore be well considered ; and should not extend 
much beyond the Chincha islands as the northern limit, and Paquica, in 
Bolivia, as the southern. 
The relative estimation of g\iano and nitrate of soda among the 
Peruvians is well shown by the following facts communicated to me by 
Mr. Bland : — "Near the coast of Peru, about 45 miles from Iquique 
(the shij)ping port of guano), there is the chief deposit of nitrate of 
soda. Tlie farmers, who collect and purify this natural product, carry 
it to the place of shipment, and always require to be paid in return with 
an equivalent quantity of guano, with which they manure their land, to 
the exclusion of the far cheaper nitrate of soda. We cannot be surprised 
VOL. V. U 
