Absorption of Potash by Soils of known Composition. 341 
Potash, calculated as Sulphur of Potash. 
Soil No. 7. Soil No. 12. 
Grains. Grains. 
Before contact with soil the solution contained 42-4896 .. 42-4896 
After contact 11-7939 .. 11-3347 
Difference 30-6957 31-1549 
1000 grains from field No. 7 absorbed 4*7148 of potash, equal 
to 8 7702 of sulphate of potash. 1000 grains of soil from field 
No. 12 absorbed 4'8088 of potash, corresponding to 8'9014 
grains of sulphate of potash. On comparing these results with 
those previously obtained on the same soils with carbonate of 
potash, it appears that potash was not separated in so large a 
proportion from its combination with sulphuric as from that with 
carbonic acid. 
Experiment No. 3. — On the Sulphate of Potash on a Marly Soil. 
The soil in this instance was the same on which the experi- 
ment with caustic potash had been made. lib. of this soil was 
mixed with 8 decigallons of distilled water and 120 8 grains of 
pure sulphate of potash. The greater portion of the solution was 
drawn off after standing four days. 2 imperial pints of the per- 
fectly clear solution on evaporation to dryness gave a residue, 
weighing 37 - 77 grains, dried at 300° Fahr. 
This residue, on analysis, gave the following results : — 
Grains. 
Organic matter and water of combination (loss on "I -,.,.qn 
heating) .. ../ ^ 
Soluble silica .. .. -050 
Oxides of iron and alumina, with traces of phos-0 
phoric acid / u 
Sulphate of lime 12-294 
Sulphate of magnesia *617 
Sulphate of potash 22-272 
Chloride of potassium '470 
Chloride of sodium -390 
37-833 
According to these determinations, the total solution (8 deci- 
gallons) after contact with 1 lb. of soil, contained : — 
Grains. 
Organic matter and water of combination .. .. 5-408 
Soluble silica -160 
Oxides of iron and alumina, and traces of phos-'l 
phoric acid J 
Sulphate of lime , 39*340 
Sulphate of magnesia 1-974 
Sulphate of potash 71 - 270 
Chloride of potassium 1-504 
Chloride of sodium 1-248 
121-064 
