CAPILLARITY 165 



paper, mops, and lampwicks are common instances, while 

 plants and the soil furnish other examples which may be less 

 understood. The stalks of plants are composed of fine tubes, 

 while the texture of the soil is such that there are countless 

 microscopic passages in it through which water can pass. 

 See Section 164, Plant Stems, and Section 147, How Water 

 is Held in the Soil. 



Some chemical substances crystallize, leaving capillary 

 passages through which more of the solution may pass. The 

 result is that the material will creep out of the dish in which it 

 has been placed. Ammonium chloride, commonly called sal 

 ammoniac, is the best example of a creeping salt. 



References : ' 



1. 1605 : 85. Movement of Water in Soil. 



2. 1702 : 240-241. Capillarity in Plants. 



3. 1803:116-121. Capillarity. 



4. Farmers' Bulletin No. 266: 7. Movement of Water in Soils. 



5. Farmers' Bulletin No. 408 : 40-41. Capillarity, 

 a. 1606 : 48. Capillary Water. 



6. 1607 : 161-174. Capillary Movements of Soil Moisture. 



c. 1612:41. Capillary Water. 



d. 1801 : 101-103. Capillary Phenomena. 



e. 1802 : 28-30. Capillary Action. 

 /. 1804:133-137. Capillarity. 



g. 1805:123-124. Capillarity. 



h. 1806 : 61-62. Capillary Action. 



i. 1807 : 153-155. Capillarity. 



j. 1808:112-114. Capillarity. 



Experiment 62. Capillarity. 



Apparatus: Beaker 250 c.c., two beakers 100 c.c., several 

 glass tubes of different internal diameter, lampwick, crystal- 

 lization dish 5" diameter, ring stand, asbestos mat, burner. 



Materials: Ammonium chloride. 



