296 



REPORTS ON THE STATE OF SCIENCE, ETC. 



Changes of Mechanical Energy — cont. 



Into. 

 Heat. 



The degradation of mechanical energy 

 into heat is commonly said to be due 

 to friction. An illustrative example 

 is shown at the Workshops. 



Light. 



The production of sparks from steel 

 and flint has been known since the 

 earliest times. 



From. 

 Heat. 



The slow change is illustrated by the 

 force due to the contraction of iron 

 bar. 

 The more violent change is to be seen 

 in all Steam Engines. In each case 

 the force comes from the alteration 

 in volume of substances when their 

 temperature is changed. 

 Light. 



In Crookes' Radiometer, the vanes 

 rotate owing to the difierential 

 effect of light on the polished and 

 dull surfaces respectively. 



Changes of Chemical Energy. 



Into. 



Electrical. 



Zinc and Copper in sulphuric acid pro- 

 duce an electric current when joined 

 by a wire, but heat when there is no 

 circuit. 

 Heat. 



Among numerous instances of this 

 change is the result of mixing water 

 and concentrated sulphuric acid. 

 The Thermite process. 

 Light. 



Many chemical actions produce light 

 as flashes. The action of Chlorine 

 on Acetylene is chosen as an example. 



From. 



Electrical. 



Electrolysis of Copper Sulphate solu- 

 tion and water shows the reverse 

 change. 



Heat. 



The ignition of phosphorus ; the heat 

 required for the ignition being 

 actually generated as the phosphorus 

 combines with oxygen. 

 Light. 



The action of light in producing ' a 

 chemical reaction is shown best in 

 photography ; parts of the chem- 

 istry of photography are demon- 

 strated. 



Changes of Electrical Energy. 



Into. 



Heat. 



The use of fuse wire embodies this 

 change. 

 Light. 



Actinic light such as X-rays is given 

 by a high potential current passing 

 through an evacuated glass bulb. 



From. 

 Heat. 



The reverse effect is brought about by] 

 the Thermopile. 



Energy Changes among Living Organismsi 



Into. 

 Potential Energy in Organic molecules 



of Green Plants. 

 Potential Energy. 



From. 

 Sun's Light — (Kinetic Energy). 



Kinetic — Plant Activity. 

 Energy — Animal Movement. 

 Animal Heat. 



Experiments performed by another group of boys, related to : — 

 Assimilation, Respiration, Stimuli, Animal Heat, Movement, etc. 



