306 



On Guano. 



The next analysis was by Fourcroy and Vauquelin (Gehlen's 

 Jour., vi. p. 679). Their results gave — 





Per Cent. 



- 



Urate or ammonia .... 



9 0 



0x9.1 ate of ammonia • . • 



1 n • 



lU 0 



Oxalate of lime . . , • 



i y) 



Phosphate of ammonia 



. 60 



Phosphate of ammonia and magnesia 



. 2-6 



Sulphate of potash . , . . 



5 D 



Sulphate of soda . . <, . 



3-3 



Sal ammoniac ..... 



. 4-2 



Phosphate of lime . . 



. 14-3 



Clay and sand ..... 



. 4-7 



Water and organic matters . 



. 32-3 





100 



If we suppose the analyses equally correct, the specimens 

 examined severally by Klaproth and by Vauquelin differed very 

 much in chemical constitution. That of Klaproth was mixed 

 also with one-third of its weight of sand and silica. 



To a circular, recently issued by Mr. Macdonald, the follow- 

 ing analysis is appended, but the authority is not given : — 



Per Cent. 



Bone earth ...... 30j 



Sulphates and muriates .... 3 



Uric acid ....... 15 



Ammonia . . . . . . .15 



Other organic matter ..... 36^ 



100 



This also differs materially from the other two ; and, allowing 

 for slight errors in analysis, shows that the substance varies widely 

 in composition. It cannot fail, indeed, to vary to some extent, 

 according to the state of decay in which it is subjected to ex- 

 amination. 



Of the guano which has been imported into this country a box 

 having been obligingly sent to me by Mr. Macdonald of the 

 average quality of that which, as he states, is likely to be here- 

 after brought to England, I have submitted it to a chemical ex- 

 amination, in reference chiefly to its economical value. It is of 

 a brownish-red colour, is evidently a very ancient deposit, and 

 has undergone much decomposition. It consists of a powdery 

 portion mixed with lumps of various sizes. The latter, when 

 broken, exhibit an aggregation of minute crystalline plates, are 

 much richer in ammonia than that which is in powder, and are 

 freer from sand and stones. When broken up, however, the 

 lumps speedily lose their crystalline appearance, give off ammo- 



