WATERPROOFING 187 



b. Melt some paraffin by gentle heat and dip the 

 tube into it. Warm the tube gently until the paraffin is 

 spread in an invisible layer up inside it, without stopping 

 the hole. This makes the hole smaller and you might 

 expect that the water would go higher in it. When the 

 tube is cold place it in the water. Where is the surface 

 of the water inside the tube? 



This is the principle by which raincoats keep out the 

 rain. The goods are porous but there has been produced 

 a change in the threads so that capillarity has been de- 

 stroyed. It is impossible to wet anything beneath the 

 surface unless capillarity acts. Why do you wet a mop 

 before using it? 



75. Flavoring Extracts and Perfumes. 



The making of flavoring extracts and perfumes are 

 examples of solution by special solvents. In this case 

 alcohol is the solvent. Vanilla extract may be made by 

 grinding vanilla beans in a meat chopper and allowing 

 the mass to soak in a mixture of one-half pure alcohol 

 and one-half distilled water, in a stoppered bottle for 

 several days. A small amount of sugar may aid the 

 solution. This will produce a delicately flavored extract 

 at a moderate price. 



Grate off the outside of several lemons, or oranges, 

 and soak the gratings for several days in pure, undiluted 

 alcohol if you wish to make lemon or orange flavoring 

 extracts at a slight price. 



Many perfumes may be made by allowing the mate- 

 rial, whose perfume is desired, to soak for several days in 



