318 Intelligence and Miscellaneous Articles. 



This analysis differs considerably from that of Fourcroy and Vau- 

 quelin, made in 1804, and from the more recent one of M. Wohler. 

 The above composition of guano is at any rate almost identical with 

 that of the excrement of aquatic birds and of poultry, and it throws 

 great light on the origin of this substance. It is evidently the excre- 

 mentitious product of birds, but according to the observations of M. 

 de Humboldt, the Ardea and the Phcenicoptera, which inhabit the 

 South Sea Islands, could not produce such great masses of guano 

 as those which exist in these islands ; it is evident, in the opinion of 

 MM. Girardin and Bidard, that guano does not belong to the pre- 

 sent system, but is a coprolite or fossil excrement of antediluvian 

 animals. 



The presence of carbonate of ammonia in the fine powder is en- 

 tirely accidental. It is probably the result of the decomposition of 

 the urate of ammonia, which readily occurs by exposure to atmo- 

 spheric moisture. 



This opinion is strengthened by the fact, that the gravelly sub- 

 stance, when exposed to the air, breaks up and falls to powder, 

 containing much carbonate of ammonia, which may be isolated and 

 sublimed by a gentle heat. Of all the principles which guano con- 

 tains, the uric acid and the ammonia are unquestionably of the great- 

 est importance ; it is to their abundance that the marked fertilizing 

 power of this valuable substance is to be attributed. 



If, as can scarcely be doubted, the value of manures depends 

 greatly upon the quantity of azote which they contain, and if the 

 rapidity of their action upon vegetation is in direct proportion to the 

 facility with which they yield their soluble or gasefiable principles 

 to plants, it is easy to comprehend the superiority of guano over 

 the greater number of manures, and the quickness with which it acts. 

 It is absolutely in the same condition as pigeons' dung, the chemical 

 nature of which is identical, except a smaller proportion of ammo- 

 niacal compounds. 



In order to determine the value of guano as a manure, the authors 

 determined, with the greatest care, the quantity of uric acid and am- 

 monia which it contained; and the analysis showed that 100 parts 

 of it contained 



Dry uric acid 18'4 representing 6*13 of azote 



Ammonia 130 ... 10'73 ... 



Consequently 100 of guano represent. . 16*86 

 The proportions of uric acid and ammonia in guano may vary ac- 

 cording to the degree of alteration which it has undergone, convert- 

 ing a portion of urate into carbonate of ammonia, the volatility of 

 which facilitates its continual loss. This is the only way in which 

 the considerable differences can be explained, which exist, the authors 

 observe, as to the azote, in their results and those of MM. Boussin- 

 gault and Payen, who, in fact, found only 4*97 per cent, of azote in 

 rough guano and 5*39 per cent, in the separated and sifted powder, 

 so that while MM. Boussingault and Payen give 7 '41 as the equiva- 

 lent of guano, MM. Girardin and Bidard give 2"37. — Ann. de Ch. et 

 de Phys., Janvier 1844. 



