42 INTRODUCTION TO GENERAL SCIENCE 



29. COOKING 



There is one other effect of heat which civilized man em- 

 ploys, and which is a strong civilizing influence : heat changes 

 food so as to render it more soluble in the digestive juices, 

 and at the same time kills all microbes in the food, thus pre- 

 venting disease from entering the system. Cooking, which 

 is the result of the application of heat to food, falls under 

 two general headings boiling and baking. Boiling has the 

 advantage of constant temperature, which is, ordinarily, 212 

 Fahrenheit. Fast boiling is not hotter than slow boiling, if 

 the dish is uncovered. Covering a dish raises the tempera- 

 ture of the boiling water, since the cover prevents rapid 

 radiation of heat. 



Roasting or baking takes place at varying temperatures, 

 according to the kind of food which is being cooked. It is to 

 be remembered that it is the temperature which does the 

 cooking, or, to put it another way, the chemical changes which 

 are called cooking take place at a certain temperature for 

 a given kind of food. Therefore, if we can only keep food 

 hot, without a fire, that food will be cooked just as well as it 

 would be in a stove. This is the principle of the so-called 

 fireless cooker. After the food to be cooked has been heated 

 to the boiling point, we place it in receptacles surrounded by 

 nonconductors of heat; thus the heat which is already in the 

 material stays there, and chemical changes take place which 

 result in cooking. It is not necessary to have elaborate 

 fireless cookers. Boxes well packed with excelsior, or felt 

 from a hat manufactory, and provided with a tight-fitting 

 cover, also well packed, will serve. 



Here are a few of the principles of cooking : 



