PROBLEM 180 213 



c. Test for Copper 



Materials. Canned peas or beans, beaker, hydrochloric acid, 

 iron nail. 



Method. Place half a spoonful of mashed canned peas or 

 beans in a beaker containing one spoonful of water and 10 drops 

 of hydrochloric acid. Set the beaker in a dish of boiling water. 

 Drop a new iron nail into the mixture. Boil for ten minutes. 

 Stir constantly. 



Observations. What color does the nail turn ? (See note, page 

 212.) 



Conclusion. Is copper present in the material tested? 



d. Are Eggs Fresh? 



Materials. Egg, salt solution. 



Method. Make a weak (10 per cent) salt solution. Place 

 eggs to be tested in the solution. 



Observations. Do the eggs you test float? If so, they are 

 fresh. 



Conclusion. Are the eggs tested fresh ? 



e. To Test Milk for Formaldehyde 



NOTE. Formaldehyde is an unlawful adulterant. 



Materials. Milk, beaker, hydrochloric acid, ferric chloride. 



Method. Put in a beaker a teaspoonful of milk from the dairy 

 that supplies your home or lunch room. Add twice the amount 

 of hydrochloric acid to which a drop of ferric chloride has been 

 added. Mix by rotating the beaker gently. Place the beaker in 

 a pan of boiling water and leave for 5 minutes. 



Observations. If there is a purple or lavender color, formalde- 

 hyde was present in the milk. 



Conclusion. Is formaldehyde present in the milk tested? 



Problem ISO: To determine the effect of alcohol upon raw 

 white of egg. 



Materials. White of egg, alcohol, test tubes. 



NOTE. In chemical and physical composition the white of egg is nearly 

 like protoplasm. 



