Absorptive Pivpaiies of Soils. 
499 
First Analysis — 
Caiboiiate of I^imc. 
1500 gi-s. gave 1-66 equal to O'GlG lime in 1000 
Second Analysis — 
1500 grs. „ 1-64 ,, 0-619 
Moan of" the two Analyses I 0"6175 
Equal to 17 '290 in 2S,000 grs. liquid. 
Lime in 28,000 grs. original lime-water 27*91G 
Ditto after 2 hours' digestion with the soil 17*290 
Absorption of 2000 grs. soil 10 '626 
Or an absorption of 5'3I3 by 1000 grs. 
Experiment No. 7. 
A third quantity drawn off after 24 hours' digestion. 
First Analysis — 
Carbonate of Lime. 
1-63 equal fo O'GOS lime in 1000, 
Second Analysis — 
1-64^ „ 0-616 „ 
Mean of the two Experiments .. 0'6I2 ,, 
EciUal to 17-136 in 28,000 grs. liquid. 
Lime in the original 28,000 grs. lime-water 27*916 
Ditto after 24 hours' digestion with the soil 17*136 
'Absorption by 2000 grs. soil 10-780 
Or an absori)tion of 5" 390 by 1000 grs. soil. 
In the case of this soil it would appear that a prolonged diges- 
tion with lime-water has no kind of effect upon the amount of 
lime removed from solution — the solution examined after 24 
hours' digestion gives precisely the same results as when the 
contact of the materials has only lasted 1 hour. Tiiat the second 
Experiment does not give the same result is obviously du(5 to 
eiTor ()f analysis, and when we find tliat one-hundredth of a grain 
in the weighing is enough to account for the difference, we cannot 
be surprised that it should occur. We must conclude then that 
in the case of the soil No. 15, it is immaterial whether it is left 
to digest with the lime-water for 1 hour or 24 — the result is the 
same in either case. It will be observed that the absorption by 
this, the top soil of the London clay, is on the average of the 
six analyses now given only 5* 3G4 grs. of lime for every 1000 grs. 
of soil, whereas in the case of tlie soil No. 4, which is the surface- 
soil of the gault clay, the full absorption was 10* 577 grs. by 
1000 grs. of soil, or as nearly as possilile double the quantity. 
This circumstance is, however, in great part accounted for by the 
iact that the soil No. 4 contains a good deal of sand and small 
pebbles which cannot, of course, take part in the absorption and 
<liminish in exact relation to the quantity the effective force of the 
soil in this respect — it became necessary, therefore, to determine 
