Mingling of Molecules 263 



denatured alcohol dissolves in the water well enough, but 

 the denaturing substance in the alcohol will not dissolve in 

 water ; so it forms tiny droplets that make the mixture of 

 alcohol and water cloudy. 



The purpose of this experiment is to show that the 

 molecules of water get into the spaces between the 

 molecules of alcohol. It is as if you were to add a pail 

 of pebbles to a pail of apples. The pebbles would fill 

 in between the apples, and the mixture would not nearly 

 fill two pails. 



The most important difference between a solution 

 and an emulsion is that the particles in an emulsion 

 are very much larger than those in a solution ; but for 

 practical purposes that often does not make much dif- 

 ference. You dissolve a grease spot from your clothes 

 with gasoline ; you make an emulsion when you take 

 it off with soap and water; but by either method you 

 remove the spot. You dissolve part of the coffee or 

 tea in boiling water ; you make an emulsion with cocoa ; 

 but in both cases the flavor is distributed through the 

 liquid. Milk is an emulsion, vinegar is a solution ; but 

 in both, the particles are so thoroughly mixed with the 

 water that the flavor is the same throughout. There- 

 fore in working out inferences that are explained in 

 terms of solutions and emulsions, it is not especially 

 important for you to decide whether you have a solution 

 or an emulsion if you know that it is one or the other. 



How precious stones are formed. Colored glass is 

 made by dissolving coloring matter in the glass while it is 

 molten. Rubies, sapphires, emeralds, topazes, and ame- 

 thysts were colored in the same way, but by nature. 



