262 Prof. Clausius on the Difference between 



and the oxygen thus altered was called ozone. But, together 

 with an oxidizing action, a deoxidizing action was also then 

 observed for the first time, the deoxidation of binoxide of lead ; 

 and it w T as the publication of this observation* that led to the 

 communication of my views on ozone. 



Since then numerous and important experimental observa- 

 tions on ozone have been made. Schonbein himself has com- 

 pleted his very important discovery of ozone by proving the dif- 

 ference between ozone and antozone. Among other researches, 

 I must specially mention the highly interesting publication 

 of Meissner, Untersuchungen uber den Sauerstoff ; further, the 

 continued investigation of Andrews and Taitf, and the beautiful 

 observations made by BaboJ and Soret§. 



The results of these newer investigations have in a surprising 

 manner confirmed the chief part of my explanation ; but in two 

 points, of inferior importance however, they do not quite agree 

 with it. These deviations may perhaps with many readers raise 

 a doubt as to the accuracy of my explanation, as it is not always 

 easy to distinguish the essential from the non-essential of an 

 explanation ; and this distinction has been made the more diffi- 

 cult in the present case because, in my first explanation, I laid 

 greater weight upon a non-essential point than was necessary. I 

 consider it convenient, therefore, once more to revert to the sub- 

 ject, in order to state in how far I at present consider my expla- 

 nation correct, and in what points, on the other hand, in my 

 view, small alterations have become necessary in consequence of 

 the new investigations. 



In my paper " On the Nature of the Motion which we call 

 Heat" ||, I have drawn the conclusion that in ordinary oxygen 

 the atoms are not separated, but are joined in pairs forming mo- 

 lecules, — a conclusion which also agrees with the views enunci- 

 ated by Gerhardt " On the Constitution of the Molecules of Gas, " 

 excepting that Gerhardt has spoken less definitely about oxygen 

 than I ; for he only says^f, "the free oxygen-atom is composed of 

 several (at least two) atoms." Resting on this conclusion, which 

 I had previously drawn, I explained the active oxygen contained 

 in ordinary oxygen, which was then called ozone simply, by say- 

 ing that it consisted of individual atoms not united in pairs 

 forming molecules, which are dispersed among the ordinary 

 molecules. 



* Phil. Mag. January 1858, page 24. f Phil. Trans., 1860, 113. 



% Berichte der naturf. Gesellschaft zu Freiburg im Breisgau, vol. hi. 

 part 1. 



§ Comptes Rendus, vol. lvii. p. 604. 



|| Pogg. Ann. vol. c. p. 353. Phil. Mag. S. 4. vol. xiv. p. 108. 



^T Gerhardt, Truitede Chimie, vol. iv. p. 574. 



