266 INTRODUCTION TO GENERAL SCIENCE 



9 g. in 25 c.c. water; (2) sodium hydrate, 30 g. in 250 c.c. 

 water; (3) Rochelle salts, 43 g. in 250 c.c. water. To use, 

 take equal parts of (1), (2), and (3), and two parts water), 

 litmus paper, concentrated nitric acid, ammonium hydrate, 

 benzine or ether, powdered chalk, potato, concentrated sul- 

 phuric acid, cotton cloth for strainer. 



a. Grind or slice material to be tested, and let stand in a 

 little water. Add a few drops of iodine solution. A blue 

 color indicates starch. If the mixture turns black, add more 

 water and the blue' color will appear. 



6. Bring from home a little of rice, wheat, beans, peanuts, 

 and apple, and test each for starch. 



c. Make some potato pulp,~mix-it with water, and strain it 

 through a cloth. Let liquid stand until the solid settles, then 

 pour off clear liquid and dry the residue by gentle heat. This 

 is starch. Prove it by testing a little. Also taste a little and 

 describe its taste. Add 1 c.c. concentrated sulphuric acid to 

 75 c.c. water, and put in it some of your starch. Boil gently 

 for twenty minutes, add powdered chalk until the litmus test 

 indicates no acid, and boil for five minutes more. Filter and 

 boil in the evaporating dish to a thick sirup. Take care not 

 to burn it. Taste some. Conclusions ? Test some for starch. 

 What has happened? Save the rest for (d). 



d. Place some of the material in a little water, and warm to 

 dissolve any sugar which may be present. Add a drop or two 

 of sulphuric acid and some Fehling's solution. If, upon boil- 

 ing, the blue color changes gradually to red, grape sugar is 

 present. If test is not decisive, add more Fehling's solution 

 and continue to boil. In this way test the material from (c) 

 and also the materials brought from home. 



e. Cut the material into small pieces, and pour benzine or 

 ether on them. After a few minutes filter, and let the solvent 



