3 IS Prof. Tyndall on the Absorption and 



and 18th of last July, satisfied me that I had not over-estimated 

 its power as an absorber of radiant heat. 



In my first experiments I made use of large electrodes, for the 

 purpose of lessening the resistance to the passage of the current 

 through the decomposing liquid. The oxygen thus obtained 

 differed but little from ordinary oxygen. 



This year I had three decomposing- vessels constructed : in the 

 first (No. 1) the platinum plates had about four square inches of 

 surface, being rolled up to economize space ; the plates of the 

 second (No. 2) had two square inches of surface, while those of 

 the third (No. 3) had only a square inch of surface each. Nume- 

 rous experiments with these gave me the following constant 

 results. Calling the absorption of ordinary oxygen 1, — 



Electrolytic Oxygen. 

 From plates. Absorption. 



No. 1 20 



No. 2 34 



No. 3 47 



A series of experiments made on the following day gave these 

 results :— 



No. 1 21 



No. II 36 



No. Ill 47 



I now cut away a portion of the plates of No. II. so as to 

 make them smaller than those of No. III. The oxygen obtained 

 with these plates gave an absorption of 65, thus exceeding No. 

 III. considerably. The plates of No. III. were now reduced so 

 as to make them smallest of all ; the oxygen which they delivered 

 gave an absorption of 85. I feared the development of heat with 

 these smallest plates, and, knowing heat to be very destructive of 

 ozone, I surrounded the apparatus by a mixture of pounded ice 

 and salt. The absorption of the oxygen thus obtained with the 

 smallest plates amounted to 136. 



By the results already recorded we have been prepared for the 

 effect of minute quantities of matter; otherwise we could not 

 fail to be struck with astonishment on finding a quantity of this 

 substance which would elude all attempts on the part of the 

 chemist to determine its amount, producing an effect so stupen- 

 dous in comparison with common oxygen. I have, moreover, 

 strong reason to believe that I understate considerably the effect 

 of the ozone. The experiments exhibit in an extremely striking 

 manner the great influence of the density of the current at the 

 place where the oxygen is liberated on the amount of ozone 

 developed. 



