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XVI. — On the Absorption of Potash by Soils of Known Compo- 
sition. By Dr. AugtjstusVoelcker. 
We are indebted to Professor Way for a series of remarkable 
experiments, showing that soils not only possess the power of 
abstracting free potash from its solution in water, but are 
capable also of separating this important alkali from its saline 
combinations. Since the publication of Professor Way's inte- 
resting and highly valuable Papers " On the Absorbing Properties 
of Soils," I have been engaged in studying the changes which 
liquid fertilizing matters undergo in contact with soils of known 
chemical composition.* 
As a further instalment to these soil-studies, I have now the 
pleasure of recording the results of experiments made with a view 
of ascertaining to what extent soils of various chemical characters 
absorb free potash from its solution in water, and to what extent 
the same soils separate potash from its soluble salts and retain 
it in a comparatively speaking insoluble state. 
1. Series of Experiments on the Absorption of Caustic 
Potash. 
Clay soils, it is well known, possess in a high degree the power 
of absorbing potash, and this they are generally considered to 
exert with greater or less avidity according as the clay varies 
in stiffness. On the other hand, sandy soils are believed to be 
deficient in this power of fixing potash, which next to phos- 
phoric acid and ammonia, is, no doubt, the most valuable fer- 
tilizing constituent. These conclusions confessedly rest on a very 
limited range of experience, so that any additional information 
on this subject will be of some use. The soils selected for the 
following six experiments were : — 
1. A calcareous soil. 
2. A stiff clay. 
3. A fertile sandy loam. 
4. Soil from a pasture, being a vegetable mould, containing 
abundance of organic matter, and a fair proportion of sand 
and clay. 
5. A marly soil. 
6. A sterile sand, containing a good deal of organic matter 
and scarcely any lime. 
* The results of experiments oa this subject have been published by me in this 
Journal, in Papers bearing the respective titles : " On the Changes \rhich Liquid 
Manure undergoes in Contact with Soil;" "On the Chemical Properties of 
Soils ; " and " On the Absorption of Soluble Phosphate of Lime." 
VOL. XXV. 2 B 
