Ozone and the Atmosphere. 203 



The action upon India-rubber is very energetic, especially 

 when under strain. This may be illustrated as follows : A 

 piece of black rubber tubing is coiled tightly around a glass 

 rod, and placed in a bottle through which a current of ozo- 

 nized oxygen is allowed to flow, the gas entering at the bot- 

 tom and escaping at the partially closed top. The black color 

 disappears quickly, a dirty yellow following, and the surface 

 becomes roughened. In a few minutes the edges are serrated, 

 cracks open until the whole tube yields, and it falls into more 

 or less ring-like fragments. 



To determine more accurately the amount and kind of 

 change produced in rubber, it was exposed to a slow current 

 of ozonized oxygen (30 litres) for a number of hours. The 

 gas, after passing over the rubber, was made to flow through a 

 weighed sulphuric acid tube, then through a Liebig's bulb and 

 sulphuric acid tube, then through another sulphuric acid tube 

 acting as a guard, and finally through 3 Geissler bulbs, con- 

 taining solutions of potassium iodide. The time and difficulty 

 in making so many joints tight, by the aid of paraffine, were 

 great. The results were as follows : 



Porcelain boat + rubber after ozonizing = 7.2523 grains. 



" + " before " = 7.2415 " 



Increase due to action of ozone = 0.0108 " 



Sulphuric acid tube after ozonizing = 12.745 " 



" '- before " == 12.7-39 " 



Increase (probably water) — 0.006 " 



Potash bulbs after ozonizing == 14.620 " 



" " before " = _14.6094 " 



Increase (probably carbonic acid) = 0.0106 " 



The first Geissler bulb was dark yellow, the second light 

 yellow, the third colorless. The liberated iodine corresponded 

 to 2.47 mgrm. ozone. The above experiment is far from 

 being conclusive, and is given principally to show the need of 

 investigation into the nature of the changes occurring in rub" 

 ber and other organic bodies, under the action of ozone. 



Preparation by Chemical Methods: The most noteworthy 

 result arrived at in an examination of these methods, was the 



