THE CHEMISTRY OF THE KITCHEN. 373 



action and partly disappear ; the pectose is resolved into 

 soluble pectin and other fruit products of the nature of 

 gelatine, which, by the chemistry of the kitchen, in cooking, 

 is converted into the many forms of fruit jellies ; the starch is 

 changed into glucose or grape sugar by the action of the 

 nitrogenized diastase which they contain. Fruit is tender 

 and perishable. The process of ripening, unless arrested, is 

 soon followed by loss of flavor, deterioration, fermentation 

 and decay, when it becomes very unhealthy and dangerous 

 to eat. It would be in accordance with sound dietetic wis- 

 dom if ripe, wholesome fruit formed a part of every meal. 

 Izaak Walton said, " Doubtless God could have made a 

 better berry than the strawberry, but doubtless God never 

 did," an opinion most people would assent to ; others might 

 prefer an apple, a pear, an orange or a banana. Most vari- 

 eties of fruit are eaten without being cooked ; others are 

 made into sauces, jellies, pies and pickles. Some are pre- 

 served by drying ; others by the modern process of canning, 

 which has been developed into a great industry, and applied, 

 in the chemistry of the kitchen and in large establishments, 

 for the preservation of fruits, milk and meat of all kinds. 



The demand for drink is manifested by sensations of 

 thirst, and is more imperative than our desire for food. A 

 man will live longer and suffer far less without food, than 

 he will when deprived of drink. In relieving our thirst we 

 are guided largely by the inexorable demand for gratification 

 of the imperious palate, which has led to the use of infusions 

 of vegetable substances, fermented and alcoholic drinks in 

 many forms, and aerated waters combined with a great va- 

 riety of fruit and vegetable syrups. 



In the chemistry of the kitchen, water used for drink is 

 partially purified by boiling, which drives off* the gases and 

 changes the organic matter it may contain, destroying its 

 poisonous properties, and eflfectually kills the germs of 

 specific diseases that may be present, like those of cholera, 

 typhoid fever and intestinal entozoa. 



The almost universall}'- used infusions of tea and coffee are 

 prepared in the kitchen. Their consumption is enormous. 

 The active principle of tea — .48 per cent. — is called theine. 

 It also contains tannin, — 18 per cent., — and an essential oil 



