192 GUANO. 



mended. For this purpose, one part of bird-manure 

 should be .treated with at least from 80 to 100 parts 

 of water ; since, if too strong, the solution of guano 

 exerts a corrosive action upon young and tender 

 plants. 



For top-dressing, which should be employed, as 

 circumstances may make advisable, in the autumn 

 or early spring, guano is in like manner most judi- 

 ciously employed when mixed with earth. 



3. Tests for Guano. 



As the previous analyses show, a guano may be 

 perfectly genuine and yet miserably had ; how great, 

 then, the liability to disappointment, when intention- 

 al adulterations^ which render a good guano compar- 

 atively worthless and a bad guano still worse, are 

 superadded! Under these circumstances, it cannot 

 be too strenuously recommended to the farmer, that, 

 if he does not wish to spend his money uselessly, he 

 should buy guano from such sources only as are known 

 to be trustworthy, or after a previous chemical exami- 

 nation. If he is not afraid of a little time and 

 trouble, he can institute a trial for himself with very 

 great facility. Tests are now possessed of such sim- 

 plicity as to require in their application scarcely 

 more dexterity and attention than in roasting or 

 boiling coffee, and yet sufficiently accurate to serve 

 in doubtful cases as a reliable means of information. 



1. Drying and subsequently Washing ivith Water, 

 If the guano, as is generally the case with those va- 



