156 AMERICAN MANURES. 



the salts of ammonia are soluble in water, and 

 are directly available as plant food. Ammonia 

 is contained in .Peruvian Guano, as actual and 

 potential, in about equal proportions. 



Professor Johnson says, " Peruvian Guano is 

 genuine and good when it contains 15 per cent, 

 of ammonia, and the same amount of phosphoric 

 acid." About one-third of this acid is soluble in 

 water; it also contains an average of 3 per cent, 

 of potash ; and at the prices quoted below a ton 

 would show a value, as follows : 



7 per cent, of Potential Ammonia, 150 Ibs. @ 15 cents, 

 7* " " Actual Ammonia, 150 " @ 25 <' " 



5 " " Soluble Phosphoric Acid = 100 " @ 12 < 

 10 " " Insoluble, as in bones, = 200 " @ 4J fl 

 3 " " Potash 60 " @ 8 < 



,..$22.50 

 ... 37.50 

 ... 12.50 

 ... 9.00 

 ... 4.80 



$86.30 



The price of the first grades of Peruvian Guano 

 is now from $70 to $75 per ton; but as that 

 which is now offered in the market contains 

 about 3 per cent, less of ammonia than the above, 

 this difference in the percentage of ammonia 

 would lessen the value $12 per ton, thus mak- 

 ing the calculated value, and the present price 

 asked by dealers, very nearly the same. But 

 when farmers pay $75 per ton for Peruvian 

 Guano, they should be very careful to know the 

 amount of ammonia, phosphoric acid and pot- 

 ash it contains; and from the amount of these, 



