J'hoqihatie Jfamtres for Boot-Crops. 
53 
solutions holding soluble phosphates, do not, after twentr-fonr 
hoars, absorb that substance as fireelj as the soils preriouslv 
operated upon. 
Absorption of SobMe Phosphate by a Marly SoiL 
ExPKRLJCEXT F. — ^The soil emplored in the foUoving; expeii- 
ment, oo analvsis^ was found to consist, in 100 parts, of — 
:i[aistiiie 4-73 
OigMiic martar and waiet oi OMnhiiantm 11-03 
Oxidesofinia 9-93 
Almiuiia .. .. .. .. .. .. .. 6-06 
Outnnateaflime r .. .. 12-10 
Solpbateof lime -75 
Uagnfig* •"'^ I'4i3 
Sohilile alica (sofaiUe in caustic pota&ii) 17*i<3 
InadoUe alioeoDS matter (dueflj dby) .. .. 3€xO 
100K» 
16,000 grains of this soil were mixed with 21o'59 grains of 
snperphosphate and placed in a bottle, and with 20,000 grains 
of distilled water.. During the first three days the bottle-contents 
were frequentlr agitated : 8000 grains more of distilled water 
were then added, and therebv the solution made np to -4 deci- 
gallons. The liquid was next allowed to stand at rest, and, afita 
seven davs from the commencement o( the experiment, 5000 
grains of the solution were drawn <^ and the perfectly clear 
solution evaporated to a small bulk. In the concentrated liquid 
the soluble phosphate was determined in the usual way, and 
found to amount to -oS grains : — 
The amoont of soloUe bane-eaidi in 4 ded^Dcnsl r-g.j? 
of soUutioD, b^bre contact with sail, was .. .. j 
In 7 days, tl^re lemuned in the sofaitkia .. .. 2-13 
Bone-earth afaeorbed by the soil 77-30 
Thus nearly the whole amount of soluble phosphate became in- 
soluble on remaining in contact with this soil for seven davs. 
The same experiment was repeated in precisely the same manner, 
and the solution left in contact with the soil for fonrteen days ; 
at the end of which time it contained oidv 1'06 grains, the soil 
having absorbed 78-37 grains. 
Marly, like chalky soils, it appears from mv experiments, have 
a much greater power than others of absorbing soluble phosphate 
— in other words, of rendering soluble phosphate insoluble. 
The 1 ime in soils of that description is unquestionablv the sole 
