No. 1 1. Suggestions for comparative experiments with Guano, SfC. 33 1 



medical man, on all intricate subjects, as he 

 would in case of a disease amongst his cattle 

 and stock, or if one was out of health in his 

 own family. 



Suggestions for comparative experiments 

 with Guano and other manures. 



In addition to the foregoing, we take the following 

 from the Appendix to Johnston's Agricultural Chem- 

 istry and Geology. It will be observed, that while the 

 Farmer's Magazine ascribes to guano a volcanic origin, 

 Professor Johnston speaks of it as an animal produc- 

 tion. The farmer will leave this point for others to 

 settle, while he is careful to look around, and see if 

 his individual interest may be promoted by the use of 

 this extraordinary article, when it shall come within 

 his reach. — Ed. 



Guano is the name given in South Ame- 

 rica to the dung of the sea-fowl, which hover 

 in countless flocks along the shores of the 

 Pacific, and which, from time immemorial, 

 have deposited their droppings on the rocks 

 and the islands which are met with along 

 the coast of Peru. 



Besides the fresh white guano which is 

 deposited year by year in these localities, 

 there exist, in some spots, large accumula- 

 tions more or less buried beneath a covering 

 of drifted sand, which have been thus buried 

 and partially preserved from an unknown 

 antiquity. This ancient guano is of a brown 

 colour, more or less dark, and forms layers 

 or heaps of limited extent, but which are 

 said sometimes to exceed even 60 feet in 

 thickness. 



In the time of the Incas, this substance 

 was known and highly valued as a manure, 

 — the country along the coast, for a length 

 of 200 leagues, was entirely manured by it, 

 — the islands on which it was formed were 

 carefully watched and preserved, — and it 

 was declared to be a capital offence to kill 

 any of the sea-fowl by which it was depo- 

 sited. Ever since that time it has been 

 more or less employed for the same purpose, 

 and much of the culture now practised on 

 this thinly-peopled coast, is entirely depend- 

 ent for its success, if not for its existence, on 

 the stores of manure which the sea-fowl thus 

 place within reach of those parts of the coun- 

 try which are susceptible of cultivation. 



In modern times, however, the access of 

 foreign shipping, and the want of careful 

 protection, have driven away many of the 

 sea-fowl, and lessened to a very great de- 

 gree, the production of the recent guano. 

 Thus the country is more dependent than 

 in former times, on the more ancient depo- 

 sits, which are now assiduously sought for, 

 and when discovered beneath the sand, are 

 carefully excavated and transported to the 

 sea-ports for sale. 



The dung of birds of all kinds, when ex- 

 posed to the air, gradually undergoes decom- 

 position, gives off" ammonia, and acquires a 

 brown colour. As this ammonia is one of 

 the most fertilizing substances it contains, 

 it will be readily understood that the old 

 brown guano is much less valuable as a ma- 

 nure, than that which is recent and white ; 

 hence the care of the ancient Peruvians in 

 collecting the fresh, and their comparative 

 neglect of the ancient guano. 



When the brown guano is put into water, 

 a large quantity of it — sometimes 70 per 

 cent, of the whole — is dissolved. Hence it 

 is, because the climate of Peru is so dry and 

 arid, that in the plains rain scarcely ever 

 falls, that the guano can accumulate as it is 

 found to do. North and south of this line of 

 coast, where rains are less unfrequent, such 

 accumulations are not met with, though the 

 birds appear equally plentiful, and it may be 

 safely stated that, had the climate of Peru 

 been like that of England, the rains would 

 have washed the guano from the rocks al- 

 most as rapidly as it was deposited. 



Of the brown guano, several cargoes have 

 lately been brought to England by an enter- 

 prising merchant in Liverpool, and it has 

 been deservedly recommended to the atten- 

 tion of British agriculturists. It has already 

 been tried upon various crops, both of hay 

 and corn, upon turnips also, and upon hops, 

 and there can be no doubt whatever, that in 

 our climate, as well as in that of Peru, it is 

 fitted to promote vegetation to a very re- 

 markable degree. 



This brown guano varies much in quality, 

 according probably to the degree of exposure 

 to the air to which it has been subjected, or 

 to its position in the deposit from which it 

 has been dug. Two different portions, taken 

 at random from the same box, gave me the 

 following very different results : 



1°.— Water, salts of ammonia, and organic matter, 

 expelled by a red heat. - - 23.5 per ct. 



Sulphate of soda, .... 1.8 " 



Common salt, with a little phosphate of 



soda, 30.3 " 



Phosphate of lime, with a little phos- 

 phate of magnesia and carbon- 

 ate of lime, 44.4 " 



100* 



-Ammonia. = 7.01 



Uric acid, - - - = 0.8 | 

 Water, carbonic and oxalic J 59.3 per ct. 



acids, &c, expelled by a 

 red heat, - - - = 51.5 J 

 Common salt, with a little sulphate 



and phosphate of soda, - - 11.4 " 

 Phosphate of lime, &c. - - 29.3 " 



100 



*The first contained also 8 per cent, and the second 

 lj percent, of sand, which has been left out of the true 

 composition of the guauo considered as free from sand. 



