198 Prof. Schcenbein on some Properiiek'df Ozone. 



theory of the day, the latter body as an elementary one. The 

 elementary nature of chlorine having, however, by no means 

 been proved by any decisive fact, and it being well known that 

 all the reactions produced by that body can be accounted for 

 by the theory of Berthollet, just as well as by the hypothesis 

 set up by your illustrious countryman, it seems to me that the 

 existence of ozone ought to induce chemists to reconsider the 



chiefly ifrofn reasons oi tneoretical simplicity"' 

 analogies, that chemists were determined to give up the old 

 theory and adopt the new one, cyanogen forming with mer- 

 cury a compound similar to that produced by chlorine with 

 the same metal ; cyanogen constituting with oxygen and hy- 

 drogen two acids bearing some analogy to the chloric and 

 hydrochloric acids, the readily oxidable carbon remaining, 

 even at the highest temperature, inactive towards chlorine, the 

 muriatic acid of Berthollet having never been isolated, and 

 the views of Davy ojEFering a very great facility in explaining 

 the reactions of chlorine ; these were the reasons which induced 

 chemists to abandon the old theory and admit the present one. 

 In doing so they sacrificed a sum of analogies much larger 

 than that on account of which the new hypothesis was adopted. 

 The numerous class of muriatic salts that bear so close an 

 analogy to what we call oxy-salts, could no longer be parallel- 

 ed to the latter; nay, on account of the striking resemblance 

 existing between those two classes of salts, chemists saw them- 

 selves, as it were, forced to change the views they had for- 

 merly taken of the oxy-salts and oxj^-acids, and imagine a 

 great number of compound halogenous bodies being, as to 

 their chemical character, similar to chlorine and cyanogen. 

 But up to this present moment not one of those imagined ha- 

 logenous bodies has yet been produced in an isolated state, any 

 more than the anhydrous muriatic acid of Berthollet. It ap- 

 pears, therefore, that there are at least as many arbitrary and 

 hypothetical notions mixed up with the modern views as there 

 were in the old theory, and that in this respect Davy's idea 

 does not offer peculiar advantages over that of Berthollet. 



Before entering into an appreciation of both rival theories, 

 I shall take the liberty to point out once more the very great 

 similarity existing between the properties pf ozone and chlo- 

 rine. ^ 



1 . Though we are not yet acquainted with ozone in its pure 

 condition, we nevertheless know that at the common tempera- 

 ture it exists in a gaseous state like chlorine. 



2. Ozone when concentrated has an odour very similar to 

 that of chlorine, bromine and iodine. 



