THE PUBLIC WATER, MILK, AND FOOD SUPPLY 359 



fast food, 316 cans of decaying canned food, 581 bottles 

 of impure patent medicines, 741 pounds of meat and fish, 

 12,000 pounds of hominy, 1885 cans of bad fruits and vegeta- 

 bles, and 225,000 eggs. 



In New York City in 1907, 362,795 pounds of groceries 

 and canned goods were destroyed because they were unfit 

 for use. In 1902 in the same city 12,000,000 pounds, or 

 6000 tons, of unfit food were destroyed. 



The Secretary of Agriculture estimated that in former 

 years the sale of adulterated food in the United States 

 amounted to over a billion dollars ($1,175,000,000) or about 

 15 per cent of our entire commerce in foods. Probably 

 the conditions are much better now. 



LABORATORY EXERCISE 31 



Purpose. To test foods for adulterants. 



Materials. Hydrochloric acid, iron alum, formalin, zinc, 

 lead acetate, white woolen yarn, ammonia, iodin, foods to be 

 tested. 



Directions, i. To test milk for formalin . 



In order to see what the test is, add a few drops of formalin 

 to 5 or 10 cc. of milk in a test tube. To this add an equal 

 quantity of strong hydrochloric acid and a piece of iron alum 

 about the size of a pinhead. Mix the liquids with a gentle 

 rotary motion. Place the tube in a beaker filled with boiling 

 water and allow to stand for five minutes. A purplish color of 

 the mixture shows the presence of formalin. Try the test 

 again without adding the formalin. 



2. To test meat products such as sausage and chopped meat for 

 sulfides. 



Macerate the sample with water. Pour about 25 cc. in a 

 flask and add pure zinc and about 5 cc. of HC1. If sulfides 

 are present hydrogen sulfide will be liberated. To test for 

 this, dip a piece of filter paper into a solution of lead acetate 

 and suspend it in the flask. A black precipitate on the paper 

 indicates the presence of hydrogen sulfide. 



