FRUITS 77 



much cheaper when fresh fruits are out of season. Pre- 

 served fruits are kept from fermentation by the large 

 amount of sugar which is cooked with them. They are 

 less healthful because they are oversweet and they are 

 expensive for the same reason. 1 Canned fruits depend 

 for their preservation upon the fact that all microbes 

 which would cause fermentation are killed by cooking, 

 and all others are kept out by the tightness of the cans. 

 They have about the same value as fresh fruits. Unless 

 glass cans with glass tops are used, however, there is 

 always some chance of lead poisoning, through the use 

 of a mixture of tin and lead, instead of pure tin, as a 

 coating for the sheet iron of the cans. On this account, 

 the fruit should never be allowed to remain in a metal 

 can after it has been once opened, since acids develop 

 which attack the coating of the can. 



Animal foods: milk. Of the foods contributed by 

 animals, milk is more nearly a complete food than any 

 other. It has in solution proteids in the form of albu- 

 min and casein. It also contains sugar (milk sugar) 

 together with fat in the form of minute drops. 



The casein of milk is readily separated out as a flaky 

 solid by adding to the milk a little dilute acid, or rennet 

 from a pig's or calf's stomach. When properly pressed 

 and dried, it forms cheese. 



The fat of milk rises to the top because of its light- 



1 Many of the commercial preparations contain glucose instead 

 of cane sugar. Glucose is prepared by boiling starch with sul- 

 phuric acid and neutralizing the acid with caustic lime. It is 

 wholesome if the acid is pure and is wholly neutralized by the 

 lime. Unfortunately, the acid sometimes contains poisonous sub- 

 stances, such as arsenic. Glucose is much cheaper than the 

 natural fruit and cane sugars, for which it was formerly sold. 

 As it is considered to be an adulteration of food, the law prescribes 

 that its presence must be stated on the label of the package in 

 wh^ch it is sold. To comply with the law and yet avoid the term 

 glucose, corn syrup and other pleasing names are used. 



