Absorption of Potash by Soils of hnoion Composition. 339 
on a variety of conditions. Thus 1000 grains of a soil which 
in one experiment is found to separate 561 grains of caustic 
potash from a weak solution, will take up two, three, and four 
times as much if brought into contact with a much stronger 
solution. Therefore, as in the case of caustic ammonia, the 
strength of the solution materially affects the amount of potash 
retained by the soil. Again, the relative proportions of soil and 
liquid determine in some measure the quantity of potash absorbed. 
These two circumstances, therefore, in addition to the variations 
in the purely chemical constitution of different soils, materially 
affect the result. Another striking similarity between the absorp- 
tion of potash and that of ammonia is presented to us in the fact 
that the absorption by the soil of these and, in all probability, 
of other fertilizing matters, is never complete. It does not matter 
whether a strong or a weak solution of potash is passed through 
a soil, whether more or less of liquid is employed, or in 
what way the experiment is modified, in every case the liquid 
after its passage through the soil will be found to contain more or 
less potash, showing that its complete absorption by the soil, 
even under the most favourable conditions, is impossible. 
2nd Series of Experiments. — Absorption of Potash from: 
a Solution containing Carbonate of Potash. 
I have much pleasure in recording here some careful experi- 
ments made some years ago in my laboratory by Mr. Charles 
Philips, a pupil of mine, who took particular interest in my 
investigation of the absorbing properties of soils. At my request 
Mr. Philips experimented with two soils,* which possess similar 
general characters, but differ chiefly in the proportions of car- 
bonate of lime which they contain. Both are calcareous clay 
soils, of moderate depth, and tolerably open character. They 
both contain clay in preponderating proportions, and hardly any 
sand which can be separated by washing. Submitted to analysis 
by Mr. Philips they gave the following results : — 
A. Mechanical Analysis. 
Field. 
No. Y. No. 12. 
Moisture 8*81 
Organic matter and water of combination 8"63 
Lime 4-98 
Sand 2-82 
Clay 74-76 
13-29 
9-81 
9-17 
4-88 
62-S5 
100-00 100-00 
* Taken from fields on the farm attached to the Royal Agricultural College 
Cirencester, marked No. 7 and No. 12 on the map. 
