24 MANUAL OF GENEBAL AGBICULTUBE. 



sodium sulphate, mix thoroughly and place in the third can. 

 Saturate each, including the first and compact the surface 

 of the soil. Place the cans in a warm place for a week. 

 The first can serves as a check. At the end of the week 

 what is the difference in the appearance of the surface of 

 the soil in the three cans? Sodium carbonate though 

 white, acted chemically with the humus in the soil and 

 formed the black substance which, as the water evapo- 

 rated, was left on the surface, hence the name "black 

 alkali." The chemicals in the third can did not act chem- 

 ically, hence came to the surface forming the "white al- 

 kali." 



Again thoroughly wet the soils, adding only a little 

 water at a time so that the alkali may be washed down 

 into the soil as it dissolves. Beginning as soon as the soils 

 are in condition to work, cultivate the cans to the depth 

 of an inch every day for a week. Why does the alkali not 

 come to the surface again? 



Perforate the bottoms of the cans with a nail. Place 

 each in a separate pan and add water a little at a time 

 until about a pint of dram water is collected from each 

 can. Again pack the soil surface and place the cans in a 

 warm place for two or three days. Miter about 100 c.c. 

 portions of each of the drainage waters into separate evap- 

 orating dishes and evaporate to dryness. Is there as much 

 residue in the first sample as there is in the second and 

 third? With a stirring rod taste the first residue. Add 

 a few drops of dilute hydrochloric acid to the second resi- 

 due. An effervescence (frothing) shows carbonates pres- 

 ent. Try the first residue in the same way. Is the result 

 the same? Taste the third residue. Is it salty? Does it 

 taste like the first? Have the alkalis been washed from 

 the soil ? After the cans have stood for two or three days 

 examine their surfaces.. Do they show alkali as before? 

 Draw conclusions from this exercise as to the nature of 

 alkali and methods of ridding the land of it. 



