Absorption of Potash by Soils of known Composition. 351 
Grains. 
Organic matter and water of combination 3*936 
Soluble silica -192 
Oxides ot' iron and alumina, and traces of phosphoric acid '160 
Sulphate of lime 4-975 
Chloride of calcium 25*248 
Chloride of magnesium 2*505 
Chloride of sodium 1*113 
Chloride of potassium 67-123 
105-252 
Chloride of t>„*„.u 
Potassium. Potash - 
Before the experiment the solution con "\io4-550 G5-957 
taincd / 
After contact with 1 lb. of marly soil .. 67-123 = 42-34G 
Difference 37-427 = 23-011 
1000 grains of this soil consequently absorbed 3 - 373 grains of 
potash, or nearly three times as much as the sandy soil. 
In this instance, as in all others, no absorption of chlorine 
took place. 
Chlorine. 
Before filtration the liquid contained 49-819 
After filtration through the soil 50-680 
Absorption of Potash from a Solution of Nitrate of 
Potash. 
Under this head I have to mention only one experiment, 
made upon the same clay-marl that was used in several of the 
preceding trials. 
1750 grains of this soil were shaken up in a bottle with 
7000 grains of a nitre-solution containing 25*55 grains of 
nitrate of potash. After standing three days the liquid was 
filtered off, and potash and nitric acid determined in separate 
weighed quantities of the perfectly clear solution. 
For the determination of potash the usual method was em- 
ployed, and the nitric acid was determined by Dr. Pugh's 
excellent process. 
The following were the results of this experiment : — 
Hitric Acid. Fotash.* 
Before filtration the solution contained .. 13 - 657 = 11*893 
After filtration through the soil, it contained 13 - 545 = 5*285 
Difference *112 = -6*608 
It will be seen that the liquid after filtration through the soil 
contained very nearly the same amount of nitric acid as the 
original nitre-solution. The difference in the results amounts to 
only about one-tenth of a grain, and is smaller than it would have 
2 C 2 
