PROJECTS 577 



(c) Soak the stain in lemon juice. Apply common salt and pow- 

 dered starch or salt and expose to the sun. 



(d) Keep the stain wet with Javelle water and expose to the sun. 



(e) Wash the stain with Ivory soap or any pure white soap. Rub 

 in powdered chalk with a flannel cloth. Cover with more chalk 

 and lay in the sun. 



(/) Dissolve two teaspoonfuls of shavings of any hard white soap 

 in four teaspoonfuls of water, add a teaspoonful of starch, one half 

 teaspoonful of salt, and the juice of half a lemon. Mix thoroughly 

 and apply to the mildewed stain with a brush. Keep the spot wet 

 with this mixture until the stain disappears. 



Of these six methods, 6, c, and/ are probably the most commonly 

 used. 



PROJECT XIV. How to Test Fabrics with Acids and Bases, 

 pages 55-57 



There are numerous ways of testing fabrics to determine what 

 they are made of. Experts can easily distinguish the fibers of silk, 

 wool, cotton, linen, and other fabrics under the microscope. The 

 various fibers have their characteristic appearances and odors while 

 burning that may be observed and distinguished by experimenta- 

 tion. Very reliable tests may also be made with the aid of certain 

 acids and bases. 



To Distinguish between Wool and Cotton. If you are in doubt 

 as to whether a piece of goods is wool or cotton, boil a sample of it 

 for five minutes in a strong solution of caustic soda (sodium hy- 

 droxide). If it is all wool, it will dissolve completely. If it is all 

 cotton, it will not be visibly affected, except possibly to appear 

 somewhat shrunken and a bit more silky. If the fabric is mixed 

 wool and cotton, the wool will be dissolved, leaving the cotton that 

 was woven with it. If it is mixed wool and silk, the wool will dis- 

 solve first, leaving the silk. About 15 or 20 minutes more of 

 boiling will dissolve the silk. 



Caustic soda and other strong alkalies dissolve wool very readily, 

 but do not so affect cotton. In fact, cotton is treated with caustic 



