10 THE FOUNDATION Part I 



corded his observations in his essay, "Force of Electricity on the Motion of 

 Muscles." Less than half a century later it appeared that living tissues not only 

 conduct electricity but also produce it. Now rhythmically repeated waves of 

 electrical charges are received over wires connected with metal plates placed 

 against the human head, and the records of them are taken by recording mech- 

 anisms (Fig. 16.23). The existence of electrical brain waves is clearly estab- 

 lished. 



Energy 



Energy is the capacity for action, the ability to do. Expressions of it are the 

 jumping of fleas, the wriggling of a baby, the leap of a rabbit, the response of 

 a tear gland. Just as life is known only through matter, so energy is measured 

 only by its effect on matter, the size and the speed of a flea's jump. 



Characteristics of Energy. Heat is the commonest form of energy. This is so 

 generally true that measurements of energy can be stated in units of heat. The 

 small calorie is the amount of heat required to raise one gram of water one 

 degree centigrade at sea level pressure of nearly 15 pounds per square inch. 

 Since the gram is too small to be a convenient unit, a large calorie has been 

 adopted for general use. It is the amount of heat required to raise one kilo- 

 gram (1000 grams or 2.2 pounds) of water one degree centigrade, also at sea 

 level pressure. 



Potential and Kinetic Energy. Usually energy can be in two forms, potential 

 in the rabbit's readiness to jump, and kinetic in the actual jump. Atomic 

 energy is seemingly of a different sort. 



Potential energy is that contained in any object because of its position or 

 shape or substance. Kinetic energy is that of motion. A fish hawk (osprey) 

 hovering aloft over a lake has potential energy of position. This becomes 

 kinetic energy as the hawk cuts downward to pick a fish from the water. The 

 wiry threads wound around the eggs of certain mayflies have potential energy 

 that becomes kinetic (Fig. 2.1). They are tightly coiled as long as the eggs are 

 in the body, but they spring loose and catch on plant stems as soon as the eggs 

 are laid in the water. Living cells hold potential energy of substances such as 

 fat which may be transformed into the energy of heat. In a more particular 

 sense the energy of substances is usually called chemical energy (Fig. 2.2). 

 Energy is either stored or liberated in all chemical reactions. A coal fire is a 

 chemical reaction in which chemical energy stored millions of years ago is 

 liberated from the coal: 



coal -f O- (oxygen in the air) = CO2 (carbon dioxide gas) + energy (heat). 



Catalyzers are aids in chemical reactions, hastening them without entering or 

 being affected by them. Many of them are known as enzymes or ferments and 

 each one acts upon particular substances and under certain conditions. The 



