ACTION OF LIME AS A MANURE. 
2 3 
cannot, of course, be deduced from the above researches, but 
it is not unlikely that the bicarbonate of lime gradually 
originating in consequence of the continual slow production 
of carbon dioxide from the humus bodies, acted upon the ferric 
phosphate, converting a part of it into free ferric hydrate and 
calcium phosphate. This opinion was verified by me in the 
following manner: 
Freshly prepared precipitates of basic ferric phosphate 
containing equal quantities of phosphoric acid 0.05 gnus, in 
each case were rinsed into bottles with 200 c.c. of well water, 
mixed with 500 c.c. of saturated lime water, and a current of 
pure carbon dioxide was then guided through the bottles for 3 
days. Other bottles which had received, instead of lime waten 
an equal volume of well water were treated in the same way. 
Thereupon the solutions were decanted through purified as¬ 
bestos, acidified with nitric acid, evaporated to a small volume, 
which was tested with a solution of ammonium molybdate for 
the presence of phosphoric acid. The result was negative as 
might have been anticipated. The deposit in the bottles con¬ 
sisting in one case of ferric phosphate alone, in the other of 
this compound mixed with calcium carbonate, were then trans¬ 
ferred on to a filter. A moderately concentrated solution of 
acetic acid was poured upon both the deposits and the filtrate 
was examined as to the presence of phosphoric acid. That 
ferric phosphate which had been merely treated with carbon 
dioxide yielded only a trace of its acid to the dissolvent applied, 
while from the phosphate treated with lime water and carbon 
dioxide 0.007 grms.^iq % of the total phosphoric acid present, 
passed into the filtrate. 11 This observation proves that a 
chemical reaction must have been accomplished between a part 
of the ferric phosphate and the calcium hydrate or bicarbonate 
14 It will be understood that this quantity represents only a part of the 
phosphate which had exchanged ferric hydrate for lime, because upon treat¬ 
ment with acetic acid some of the phosphoric acid which is dissolved 
from the calcium compound, will recombine with ferric hydrate and become 
insoluble. 
