334 Absorption of Potash by Soils of known Composition. 
The potash solution used alike in all six experiments was pro- 
duced by dissolving 40-47 grains of chemically pure hydrated 
caustic potash, KO, HO, in four decigallons (28,000 grains) 
of water. The solution consequently contained '1445 per cent, 
of hydrated caustic potash, or '1213 per cent, of anhydrous 
potash. 
Experiment No. 1. — Absorption of Caustic Potash by Calcareous 
Soil. 
This soil on analysis yielded the following results : — 
Moisture 3' 62 
Organic matters 4-23 
Carbonate of lime 67*50 
Oxides of iron and alumina . . .. .. 7*54 
Magnesia - 44 
Potash and soda '79 
Insoluble siliceous matter 15*88 
100-00 
It will be observed that this soil, in which carbonate of lime 
is the preponderating constituent, contains but little clay and 
organic matter ; it is, in point of fact, a chalk marl. The potash 
solution, as stated above, was placed with 3,500 grains of this 
soil in a glass-stoppered bottle, and left in contact with it for four 
days, during which time this mixture was shaken up at intervals, 
and then allowed to settle. A decigallon of the liquid was then 
drawn off and filtered perfectly clear. The clear liquid was 
boiled with baryta water, and by this means all earthy matters 
taken up from the soil were removed. The excess of baryta 
was next removed, and the resulting liquid having been evapo- 
rated to dryness, the residue was heated strongly, and the potash 
in it determined by bi-chloride of platinum. ■ 
Anhydrous Potash (K 0). 
Before contact with the soil, 1000 grains of the) 
solution contained / "" , 
After contact -413 
Difference -800 
•8 of a grain of anhydrous potash was thus fixed in the soil from 
each lOOO grains of solution, consequently 22-40 grains were 
removed from the whole solution (28-000 grains), and fixed by 
3500 grains of soil. 1000 grains of this calcareous soil thus 
absorbed 640 grains of potash. In this experiment it appears 
that, in round numbers, two-thirds of *he potash was absorbed, 
and one-third remained in solution. 
