Ozone and the Atmosphere. 201 



was filled with phosphoric anh); dride, which gradually liqui- 

 fied, from absorption of moisture. To make sure that all 

 traces of oxygen had been removed, by entering into combina- 

 tion with hydrogen under the influence of the platinum sponge 

 in the first tube, a platinum sponge guard-tube was added, simi- 

 lar to the first, except that its anterior end, as well, was filled 

 with phosphoric anhydride. In this guard-tube, no change 

 occurred. The tests were contained in an apparatus constructed 

 as follows : — -A tube 25 c. m. long and 4 c, m. wide was drawn 

 down at its ends and fitted very tightly with rubber corks cov- 

 ered with tin- foil. Through these corks glass tubes were passed, 

 conveying platinum poles, the latter sealed to the tubes with 

 only 5 m. m. of their free ends projecting. Two tubes were 

 cemented on one side of the apparatus 6 c. m. from each end, 

 and at the distance of 12 c. m., bent down at right angles. 

 These tubes entered into small wash-bottles containing sulphu- 

 ric acid, one acting as a seal at the entrance, the other at the 

 exit, of the current of hydrogen. 



In the first experiment, one specimen of each of the iodized 

 papers was introduced into the apparatus. The hydrogen was 

 then allowed to flow until all the air in the train of purifiers 

 and driers had been displaced. Connection was made with the 

 platinum sponge tubes and a slow current was allowed to flow 

 for 3 hours. The object of continuing the current so long a 

 time, was not so much with the view of displacing the air, as 

 of thoroughly dessicating the papers. A stream of sparks was 

 then passed between the poles, which were separated by an in- 

 terval of 5 c. m. 



The papers were pierced with numerous holes, but remained 

 colorless. On opening the apparatus there was no smell of 

 ozone, but an odor as of something burnt. The papers, on 

 being moistened, developed faint blue stains at the points 

 where pierced by sparks. The experiment was repeated with 

 identical results. Either, then, it appeared, the sparks alone 

 had decomposed potassium iodide, or ozone had been formed 

 in the course qi the experiment. That the hydrogen em- 



