Mingling of Molecules 261 



When you shake the 

 oil with the water, the 

 oil breaks up into tiny 

 droplets. These droplets 

 are so small that they 

 reflect the light that 

 strikes them and so look 

 white, or pale yellow. 

 This milky mixture is 

 called an emulsion. Milk 

 is an emulsion ; there are 

 tiny droplets of butter 



fat and Other substances FIG. 146. Will heating the water make 



scattered all through the more *** dissolve? 



milk. The butter fat is not dissolved in the rest of 

 the milk, and the oil is not dissolved in the water. But 

 the droplets may be so small that an emulsion acts 

 almost exactly like a solution. 



But when you shake or stir salt or sugar in water, 

 the particles divide up into smaller and smaller pieces, 

 until probably each piece is just a single molecule of the 

 salt or sugar. And these molecules get into the spaces 

 between the water molecules and bounce around among 

 them. They therefore act like the water and let the 

 light through. This is a solution. The salt or sugar 

 is dissolved in the water. Any liquid mixture which 

 remains clear is a solution, no matter what the color. 

 Most red ink, most blueing, clear coffee, tea, and ocean 

 water are solutions. If a liquid is clear, no matter what 

 , the color, you can be sure that whatever things may be 

 in it are dissolved. 



