33 



THURSDAY, MAY 14th, 1896. 



ELECTRICAL DISCHARGE, 



BY 



Me. W. R. bower, AR.C.S., 



followed by a demonstration by 



Mr. E. CLUTTERBUCK, Ph.D., B.Sc, 



ON 



THE PHOTOGRAPHIC PROPERTIES OF 

 THE X RAYS. 



The phenomena connected with electrical discharge have 

 been the subject perhaps of more zealous and patient research 

 than those belonging to any other branch of physical science. 

 The discovery in 1745 of the Ley den Jar soon attained world- 

 wide notoriety. Sir Humphrey Davy says : " No single 

 philosophical discovery ever excited so much popular and 

 scientific attention." Among those who studied it was the 

 celebrated Benjamin Franklin, and it is to him we owe an 

 intelligent theory of electrification as a result of his experiments. 

 Poor Richard was able to announce in his almanac for 1753 th:it 

 " It has pleased God in His goodness to mankind, at length to 

 discover to them the means of securing their habitations and 

 other buildings from mischief by thunder and lightning." 



It was Franklin's discovery of the efficacy of points in 

 bringing about electrical discharge which gave us the lightning 

 rod. 



Nicholson and Carlisle in 1800 made the next great stej). 

 They found that when a continuous discharge is made through 

 acidulated water the water is broken up, decomposed into its 

 constituent gases. Sir Humphrey Davy soon took advantage of 

 the discovery, and by the electric current decoru posed the fixed 

 .alkalies and obtained the metals sodium and potassium. 



If two metallic balls form the poles of an electrical machine 

 and they be set near together we may get a short thick spark 



