50 GENERAL SCIENCE 



Experiment 8. Introduce a solution of copper sulphate 

 into the bottom of a hydrometer jar or any tall jar filled with 

 water. This may be done by pouring the solution through a funnel 

 tube which reaches to the bottom of the jar. 

 Allow the jar to stand for a few days, noting the 

 change from day to day (Figure 44). 



Experiment 9. Into a small jar put a few 

 drops of strong ammonia water and cover it with 

 a piece of paper. Into a second jar put a few drops 

 of concentrated hydrochloric acid and invert on 

 the first jar. Now withdraw the paper. The 

 chemical action which follows is evidence of the 

 FIG 44 The ra P^ diffusion of the gases. Although these gases 

 copper sulphata are not visible, their presence may be determined 



solution slowly by th e j r odors. As they diffuse, a new substance 



diffuses through . 



the entire jar, as IS formed. 



is shown by the Some few liquids will not diffuse. Devise an ex- 

 change in color. periment to ghow that oil and water will not diffuse. 



Can you put oil, alcohol, and water into the same bottle so that 

 they will not mix? How? 



Osmosis. Osmosis is the diffusion of liquids or gases 

 through porous walls or membranes. 



Experiment 10. Tie a piece of parchment or bladder over the 

 mouth of a large funnel tube, and after having filled it to the 

 depth of about three inches with a saturated solution of copper 

 sulphate, lower the funnel end into a jar of water until the level 

 of the solution in the tube is the same as that of the water in the 

 jar. Support it in this manner and allow it to stand for several 

 hours, when it will be found that the blue solution is several inches 

 higher than the level of the water in the jar. This is due to the 

 fact that although the water and the solution pass through the 

 membrane in opposite directions, the water passes through at a 

 much more rapid rate, thereby diluting and increasing the volume 

 of the solution in the funnel tube (Figure 45). The water in the 

 jar gradually acquires a blue tinge, proving that some of the solu- 

 tion of copper sulphate has passed through the membrane into the 

 jar. If the water and the solution had diffused at the same rate, 



