Active and Ordinary Oxygen. 269 



plicated molecules in pure oxygen which contain the active oxygen 

 may be supposed to be constituted. But I must here expressly 

 mention that I do not consider that which can be said upon this 

 point as necessary for my explanation, but think that the expla- 

 nation so far as it is contained in the preceding may be taken 

 even w r here different opinions are held as to the specialities of the 

 molecular constitution. Hence before I pass to these observa- 

 tions, I will once more briefly summarize the essential part of 

 my explanation in a form corresponding to the recent disco- 

 veries. The molecules of ordinary oxygen are diatomic, and each 

 contains an electro-positive and an electro-negative atom. Active 

 oxygen consists of unpaired atoms, which may either be free or 

 loosely united ; and according as the atoms are electro-positive or 

 electro-negative, they form antozone or ozone. 



All the above-mentioned observers, who have found that ozo- 

 nized oxygen occupies a smaller volume than ordinary oxygen, 

 are agreed that in the first the molecules must be more complex 

 than in the latter. This is in fact, as already said, to be regarded 

 as a direct result of those observations^ if we consider as esta- 

 blished the law that the volume of a gas is proportional to the 

 number of its molecules. But regarding the mode in which the 

 composition of the molecule is to be imagined, they are of differ- 

 ent opinions. 



Andrews and Tait connect their consideration with experi- 

 ments which they have made with compound gases, especially 

 nitrous oxide and carbonic oxide. When they produced in these 

 gases the same electrical discharges by which they had effected 

 the excitation of oxygen, they observed, as in this case, a diminu- 

 tion of volume, which they explain by assuming that the consti- 

 tuents of the gases in question under the influence of the dis- 

 charges are partially liberated from their previous compounds 

 and transformed into others which occupy a smaller volume. 

 Founded upon this, they make a supposition that oxygen is not, 

 as now assumed, a simple body, but a chemical compound, whose 

 constituents may also variously unite with one another. This 

 explanation deviates so widely from the generally received view, 

 that, as I think, it can only be entered upon when no other 

 explanation is possible. 



Von Babo holds to a view, formerly expressed by Weltzien*, 

 which is opposed to my explanation, since it tends to consider 

 ordinary oxygen as composed of simple, and ozonized of diatomic 

 molecules ; and he promises to develope his reasons in a subse- 

 quent paper. I cannot at all favour this idea, since even the 

 comparison of the volume of oxygen with the volumes of its 

 compounds led me, quite independently of ozone, to the assump- 

 * Ann. der Chem. und Pharm. vol. cxv. p. 128. 



