ACTION OF LIME AS A MANURE. 
21 
of phosphoric acid. All the bottles were then kept under a 
spacious bell glass to prevent the mixtures from drying up. 
We believe that by these arrangements we did not much deviate 
from the ordinary conditions of the fields, either with regard 
to the mode of applying the manures or with respect to the 
quantities of lime and phosphate. 
One, resp. two months after the application of the phosphatic 
manure we determined how much of the phosphoric acid had 
been converted into compounds soluble in neutral ammonium 
citrate of a specific gravity of 1.09, a reagent which is at 
present most widely used in the analysis of commercial phos¬ 
phatic fertilizers for the purpose of determining how much of 
their phosphoric acid is available for plants. The analysis 
was carried out in the usual way. The contents of each 
bottle were rinsed with 100 c.c. of neutral citrate into a small 
bulb and heated in a water bath to 30-40° C for 30 minutes, 
whereupon the solution was filled up to 250 c.c. from which 
200 c.c. were evaporated after the addition of a little cream 
of lime, and incinerated. The ash was repeatedly dissolved 
in strong nitric acid and again evaporated in order to separate 
the dissolved silicic acid. The filtrate from the latter, always 
exactly 100 c.c., was precipitated with ammonium molybdate 
and the precipitate treated in the usual way. The quantities 
of phosphoric acid dissolved from the soil by ammonium citrate, 
were found to be as follows : 
