166 INTRODUCTION TO GENERAL SCIENCE 



a. Stick several of the capillary tubes into water, side by 

 side. How does the height of rise of water compare with the 

 diameters ? 



b. Take two tubes of the same internal diameter, and place 

 one in cold water, the other in boiling hot water. Carefully 

 compare the heights of the two columns. What are your 

 conclusions ? 



c. Fill the large beaker with water, wet a lampwick and 

 bend it over the edge of the beaker, so that the longer end is 

 outside. Place the beaker in the crystallization dish, and 

 leave for a day. Compare the results with those of Experi- 

 ment 45. Why is it not necessary to start the action in this 

 experiment ? 



d. Make a saturated solution of ammonium chloride, fill 

 the small beaker half full, and set away, for a few days. De- 

 scribe the result. 



119. OSMOSIS 



All gases, liquids, and solids tend to diffuse, and, if the dif- 

 fusion is hindered, a pressure proportional to the diffusion 

 tendency is produced. If two liquids are separated by a 

 membrane which hinders the passage of one of the substances, 

 a difference of pressure is manifested. The process is called 

 osmose, and the pressure is called osmotic pressure. 



Osmose takes place naturally in seeds and roots, the sur- 

 faces of which allow water to enter, but do not allow the ma- 

 terial inside to pass out. Thus the beginning and the growth 

 of plants are dependent upon osmose. See Section 163, Plant 

 Roots, and Section 168, Fruits and Seeds. The swelling of 

 beans, when " put to soak " is due to osmose, or, as it is more 

 often called, osmosis. 



Pieces of bladder, or any animal tissue, such as gold beater's 



