EX A MI N A TION OF GUANO 141 



(2) Smell — ammoniacal. 



(3) General Condition — loose, friable powder. 



May contain fragments of stone and half- 

 decomposed feathers, etc. 



(4) Reaction — strongly alkaline. 



{b) Ichaboe Guano. 



(i) Colour — grey (see above). 



(2) Smell — ammoniacal and excretal. 



(3) General Condition — fresh, undecomposed 



feathers, and sometimes very sandy. High 

 nitrogen content. 



{c) Phosphatic Guano. 



(i) Colour — brownish red to dark brown. 



(2) Smell — practically none. 



(3) General Condition — frequently damp. Low 



nitrogen content. 



id) Equalised Guano. — A standard mixture of guano 

 made up by the importers containing about 7 per 

 cent, nitrogen. Characters as in Peruvian guano {a). 



133. Separation of Uric Acid from Guano. 



Uric acid may be extracted from guano as follows : — 

 A few grams of Peruvian or Ichaboe guano are boiled 

 with dilute caustic soda solution until there is no 

 further smell of ammonia, i.e.^ all the ammoniacal 

 compounds have been destroyed. The liquid is cooled, 

 filtered, and acidified with dilute nitric acid. The 

 precipitated material is filtered off, washed with alcohol, 

 and a small portion tested for uric acid by the 

 murexide test (see 103, p. 120). 



