FADING AND BLEACHING 23 



the halves of each piece in the dark, so that the color will 

 hot change. Wet the other halves with water and ex- 

 pose them to the bright sunlight until there is a change 

 in color. The pieces should be kept wet and it may take 

 a few days before there is much change. Make a list of 

 the colors and tell how soon they changed and what each 

 color became. 



b. Wet and expose a piece of unbleached white cot- 

 ton cloth to the bright sunlight. Compare the result 

 with another piece which has not been exposed. 



This is the old-fashioned way of bleaching and is the 

 best method, although it is slow. Bleaching may be ac- 

 complished much more quickly by the use of chemicals, 

 but the cloth is weakened and wears out more quickly. 



The sunlight changes the color of certain chemicals 

 in a strange way. We can make use of this knowledge 

 and cause the sun to print designs for us on paper. The 

 simplest paper for this purpose is called blue-print paper. 

 It may be purchased cheaply or may be made very cheap- 

 ly. See Section 70. 



Experiment 14. Blue Prints of Leaves and other 

 Articles. 



Apparatus : Piece of window glass, leaves, lace, any 

 thin article, blue-print paper at least 4"x5". 



a. Lay a piece of blue-print paper face up upon a 



