

OSMOSIS 167 



skin and skin of an egg, also show this same effect. In addi- 

 tion to the vegetable and animal membranes, there is one 

 chemical membrane which is especially useful for showing 

 osmotic pressure. This is formed by the combination of 

 copper sulphate and. potassium ferrocyanide to produce 

 copper ferrocyanide. If this compound is formed within the 

 pores of an unglazed earthenware cup, a strong semipermeable 

 cell is obtained. 



References : 



1. 1407 : 36-39. Osmosis in Plants. 



2. 1503 : 78. Expansive Force of Germinating Seeds. 



3. 1601 : 147-153. Osmosis and Diffusion in Plant Feeding. 



4. 1605:65-66. Osmosis. 



5. 1702 : 241-242. Osmosis in Plants. 



6. 1703 : 132-133. Osmotic Pressure. 



7. Farmers' Bulletin No. 408 : 13-15. How Roots Absorb 



Moisture. 



a. 1607:41-48. Osmosis. 



6. 161 1 : 2-4. The Way the Seed Gets Water from the Soil. 



c. 1612 : 47-48. Roots Take Nourishment by Osmosis. 



d. 1707 : 447-448. Osmotic Pressure. 



e. 1801 : 20. Osmosis. 

 /. 1805:117-118. Osmosis. 

 g. 1808:116. Osmose. 



h. 1809 : 92. Osmose of Gases. 



Experiment 63. Osmotic Pressure. 



Apparatus: Bottle, 6 oz., with stopper, string, porous cup 

 4" X 2", stopper to fit, with one hole, glass tube i" diameter, 

 4' long, battery jar 6"X8". 



Materials : Beans, copper sulphate, potassium ferrocyanide, 

 sugar. 



a. Fill the bottle with beans, and then fill the spaces with 

 water. Stopper the bottle tightly, and tie in the stopper. It 



