CONSTITUTION OF MATTER 



11 



still, in a very few minutes the perfume may be 



detected in the opposite corner of the 



room. Thus gases diffuse very rapidly, 



which shows the great freedom of 



movement of their molecules within 



their larger inter-molecular spaces. 



Molecules in different states. We 

 have learned that the molecules in 

 gases move much more rapidly than 

 those in liquids, and the molecules 

 in liquids move more rapidly than 

 those in solids. Likewise, the inter- 

 molecular spaces in gases are much 

 larger than those in liquids and those 

 in liquids are larger than those in 

 solids. 



Different sizes of molecules and 

 inter-molecular spaces. In the ex- 

 periment already referred to, in which 50 c.c. of 

 distilled water were placed in a burette and 50 c.c. 

 of alcohol poured carefully on top, the two thor- 

 oughly mixed were found to occupy but 98 G.C. The 

 2 c.c. had not been lost, but are accounted for by the 

 fact that the molecules and inter-molecular spaces 

 of one liquid are larger than those of the other and the 

 smaller molecules of the one were crowded into the 

 inter-molecular spaces of the other. This is the only 

 way in which this phenomenon can be explained. 



Fig. 6. Carbon 



dioxide is heavier 



than air, but it 



gradually diffuses 



into the upper 

 bottle. 



