The Chemical Relations of Water 285 



The decomposition of the water effected in the 

 above experiment was first discovered by Nicholson 

 and Carlisle in 1801, and their experiment was the 

 forerunner of many other interesting investigations 

 regarding the change of electrical into chemical energy. 

 The operation is known as " electrolysis " and the 

 liquid is called an " electrolyte ". The two plates which 

 form the gates, as it were, by which the electric current 

 enters the solution, are termed " electrodes " (Gr. odos, 

 a way). 



Incidentally this experiment has shown that two 

 volumes of hydrogen are contained in water for each 

 volume of oxygen. This volume-ratio will be confirmed 

 by the results of later work. 



197. In order to obtain a supply of hydrogen for 

 examination of its properties, a different method is 

 generally employed. 



EXPERIMENT 132. Fit up a flask as shown in Fig. 93. 

 The thistle funnel should be long 

 enough to dip to the bottom of the 

 flask, and the end of the delivery 

 tube should be inserted under a 

 beehive cell standing in water in a 

 trough. The bottom of the flask is 

 covered with a layer of zinc prefer- 

 ably in the granulated form and 

 hydrochloric acid, made by diluting 

 the strong commercial product with an equal bulk of 

 water, is poured down the funnel. A brisk bubbling of 

 the liquid at once occurs, and gas-bubbles make their 

 appearance at the end of the delivery tube. After waiting 

 a short interval to allow the air in the apparatus to be 

 displaced, collect a test-tube full of the gas issuing from 

 the hole in the top of the beehive cell. When full, close 



