34 



DIFFUSION AND OSMOSIS 



Let the apparatus stand for a few 

 hours and note the result. How do 

 you account for this? 



Conclusion. State what you infer 

 from the behavior of the contents of 

 the egg. 



The pressure which causes this rise 

 of the contents of the egg in the tube 

 is known as osmotic pressure. 



Osmotic pressure may also be shown 

 ... h by using a thin rubber bag connected 

 with a glass tube and filled with olive 

 oil. If it be immersed in a vessel 

 containing ether, the ether will pass 

 through the partition and the contents 



FIG. 10.-a, glass tube; f the ba 11 rise verV ra P idlv in the 



The bag must be surrounded 



b, sealing wax ; c, punc- tube. 



tare; d shell ; e shell 

 lining ; /, contents of 



egg ;&, glass; h, opening prevent its becoming distended. 



in shell ; i, water. 



a d()th b Q the game gize 



21. OSMOSIS 



Object. To learn how the pressure due to osmosis 

 may be measured. 



Apparatus. A potato, cork cutter, cork, glass tube bent at right 

 angles, sugar, and a shallow dish. 



Method. Cut off the lower end of the potato and remove 

 the skin about one third of the way up to the top. With the 

 cork cutter, bore a large hole to within \ to f inch from the 

 cut-off end. 



Now bore a small hole into the side of the potato above 

 the peeled area. Coat the glass tube with vaseline and force 

 it into the side hole so that leakage is impossible. 



