Literature of Ozone. 367 



and when reagents are employed which will assign true values 

 to the amount of ozone determined. 



II. The mature of the coxstitcjent matter of ozoxe. 



In his speculations upon the nature of ozone, Schonbein was 

 far less fortunate than in his multiplied inquiries into its sources,, 

 properties and applications. The difficulty at that time of pro- 

 curing air or oxygen containing more than a minute percentage 

 of ozone, and of manijDulating it when obtained, was very great, 

 so that precise quantitative investigations were attended with for- 

 midable obstacles, and probably for that reason were rarely insti- 

 tuted by Schonbein. He brought forth a variety of hypotheses, 

 thus introducing great uncertainty into a confessedly difficult 

 subject, and necessitating the labors of chemists during nearly a 

 quarter of a century for their complete overthrow. 



His earliest hypothesis was, that ozone is a compound, con- 

 sisting of hydrogen and oxygen. This, in 1844, he abandoned 

 in favor of the theory, that ozone itself is elementary, and along 

 with hydrogen enters into the composition of nitrogen, which is 

 a compound substance. 



The following year he reverted to his original hypothesis, and 

 while maintaining strenuously that ozone is not peroxide of 

 hydrogen, he nevertheless upheld the view that it is composed 

 in certain unknoAvn proportions of hydrogen and oxygen. 



The second hypothesis was overthrown by the experiments of 

 Marignac and Be la Rive, who showed that ozone could not be 

 derived from the decomposition of nitrogen, inasmuch as they 

 obtained it by passing electric sparks through perfectly pure and 

 dry oxygen. They proved the resultant body to be ozone, by 

 causing it to react on moist silver and potassium iodide, with 

 the formation of argentic peroxide and iodate of potassium. They 

 explained these reactions by supposing that, under the influence 

 of the electric discharge, the oxygen had acquired an electrified 

 condition, with exalted chemical properties, — in other words, 

 that ozone is oxygen and oxygen only, but oxygen in an electri- 

 fied state. Plausible as was this explanation, there was nothing 

 in the experiments, water having been present in the reaction 

 upon silver and potassium iodide, to confute the different inter- 



