THE FARM 301 



grains and to casein found in milk. (See pages 222, 

 and 328.) 



When a food solid is treated with strong nitric acid, any 

 protein is colored yellow. If it is then washed free of the 

 acid and dipped into strong ammonia water, the color may 

 change to orange. A piece of white silk ribbon shows these 

 same tests for protein, while a white cotton fabric is un- 

 affected. The cotton is cellulose, a vegetable fibre, and con- 

 tains no protein. 



The preservation of eggs from times of over abundance and 

 low prices to other times when the supply is much less, has 

 been solved for the large centres of population by keeping 

 great quantities of eggs in cold-storage warehouses. From 

 these storehouses they can be supplied for sale as the market 

 requires. Their food value is unchanged if they have been 

 properly cared for, though they may be somewhat less palat- 

 able than when fresh. Eggs for storage should be chosen 

 with care, and any not strictly fresh must be rejected. There 

 is much more food in a dozen large eggs than in the same 

 number of small ones, and size may very properly be con- 

 sidered in the sale price of eggs. 



The quality of an egg as to age and fitness for food can 

 easily be determined by holding the egg between the eye and 

 a strong light, preferably an electric light shining out through 

 a hole in a box within which the light is placed. This testing 

 should be carried on in a darkened room, too, so that one's 

 sight is unaffected by any light other than what comes 

 through the egg. With a little practice eggs may be graded 

 almost as fast as they can be handled since with a little 

 experience the condition of the egg is known at a glance. 



For family use on the farm the home product is often 

 stored in large jars filled with a solution of " water glass", 

 or sodium silicate, by means of which the pores of the shell 

 are closed to air and to the germs that cause decay. In 



