240-242] 



Analysis of Refuse Manures 



H7 



strong NH 3 solution are then added, and the liquid is allowed 

 to stand two hours. The magnesium ammonium phosphate is 

 filtered off, washed with ammonia, dried, ignited, and weighed 

 as usual. 



The correction necessary in this case is very small, and must 

 be obtained by measuring the filtrate and washings. For every 

 60 c.c. 1 milligram is added to the weight of the ignited 

 precipitate. 



240. Lime. — The lime is contained in the filtrate from the 

 ammonia precipitate and the washings after re-precipitation. It 

 is precipitated by ammonium oxalate and weighed as usual, 

 Should the precipitate be very small — i.e. , less than -05 gram — 

 it is ignited for twenty minutes in the Fletcher muffle and 

 weighed as CaO. 



241. Nitrogen. — Best determined by the acid method 

 (paragraphs 90-95). 



242. Calculation.— From the Mg 2 P 2 7 are calculated 

 first the P 2 5 , then the Ca 3 P 2 8 to which this is equivalent. 

 From the CaC0 3 the CaO is calculated, and from this the CaO 

 as Ca 3 P 2 8 is subtracted. The remainder is calculated back 

 into CaCO.,, and the analysis entered as follows : 



L 2 



