The Literature of Ozone. 141 



Nitrogen was announced by Mr. Stillingileet Johnson, in two 

 papers read before the English Chemical Society in 1880, to be 

 capable of existing in two allotropic modifications, his announce- 

 ment being based on an experiment in which a certain kind of 

 nitrogen, that obtained by the decomposition of ammonium 

 nitrite, had been made to enter into direct union with hydrogen 

 to form ammonia, while another kind of nitrogen, that existing 

 in atmospheric air, would not so combine. But Mr. H. B. Baker 

 has very recently shown (Chem. News, XLVIII, 187, 279), that 

 Mr. Johnson's results were erroneous, the mixed gases containing 

 oxides of nitrogen, which gave rise to ammonia under the condi- 

 tions of the experiment ; and the existence of a new allotrope 

 of nitrogen is still under discussion. 



To return from this consideration of allotropism in general, 

 and examine the thesis at the beginning of the section : — The 

 formation of ozone is to be looked for in all cases where the 

 molecule of oxygen undergoes decomposition under conditions 

 which render it possible for the constituent atoms to exist in a 

 free or uncombined condition for an interval of time. 



This setting free of the component atoms of the molecule 

 (statics nascens), always precedes the formation of ozone, inas- 

 much as before a combination of atoms by threes can occur, a 

 decomposition of the preceding combinations by twos, must take 

 place. This, it will be urged, is a self-evident proposition, and 

 I am very glad to admit that it is. But I am not the less im- 

 pressed with the importance of distinctly formulating it in this 

 place, because in much of the writing upon this topic it is ignored, 

 and also because in many places this oxygen of the nascent state 

 (free atoms), is called active oxygen and is frequently confused 

 with ozone itself. This confusion is so probable (since ozone is 

 most certainly the active allotrope of oxygen), that it appears to 

 me inexpedient to speak of nascent oxygen, as active oxygen, and 

 of the process of making it, as the activation of oxygen. To 

 guard against this danger, 1 shall term the process tlie atomation 

 of oxygen, and the freed atoms themselves, not active, but atomic 

 oxygen. But, it may be asked, what experimental proof is there 

 that atomic oxygen precedes in every instance, the formation of 

 ozone ? The answer is to be found in the fact that ozone is in- 

 capable of producing certain chemical changes, readily produci- 



