AND SCHONBEIN 47 



facts which all go to establish, in the most satisfactory 

 manner, the analogy between chlorine and my 

 ozone. 



I have no doubt that you will be astonished when 

 I tell you how ozone can be produced chemically, for 

 the conditions of its formation are such as would not 

 lead one to expect in the remotest degree the results 

 which are actually obtained. The method is this: 

 Commercial phosphorus is allowed to stand in a flask 

 filled with atmospheric air. If the temperature of the 

 experiment is only a few degrees above zero, the air 

 above the phosphorus somewhat rapidly assumes a 

 positive potential, that is, it has the power of polar- 

 izing positively a strip of gold-leaf held in it. If the 

 temperature is not raised in any way the air remains 

 in this voltaic condition and smells of phosphorus, 

 i.e., like garlic. But if the air is warmed to 8-12 

 its positive potential changes rapidly to the opposite ; 

 that is, it assumes the power of polarizing a gold-leaf 

 negatively. This change of the electrical condition is 

 accompanied by an alteration of smell. The air now 

 smells just like electricity discharging itself from a 

 point, or like the oxygen which is set free, for 

 example, on the positive pole in the electrolysis of 

 acidified water. The higher the temperature the 

 more rapid is the change which I have described; 

 and if the phosphorus is heated almost to its melting- 

 point, the alteration of smell and of voltaic condition 

 occurs in the course of a few minutes, or even in a 

 much shorter time ; while at the ordinary tempera- 

 ture several hours are required. When once the 



