606 



January 20, 1859. 



SIR BENJAMIN C. BRODIE, Bart., President, in the Chair. 

 The following communications were read : 



I. "Second Note on Ozone." By THOMAS ANDREWS, M.D., 

 F.R.S., and P. G. TAIT, M.A., F.C.P.S. Communicated 

 by Dr. ANDREWS. Received December 16, 1858. 



Since the publication of their " Note on the Density of Ozone" 

 (Proceedings of the Royal Society, June 1857), the authors have 

 been occupied with an extended investigation into the nature and 

 properties of that body. The inquiry having proved more protracted 

 than they anticipated, they have thought it proper to send to the 

 Royal Society a brief notice of some of the more important facts 

 which they have already observed, reserving a description of the 

 methods employed, and of the details of the experiments, for a 

 future communication. 



The commonly received statement, that the whole of a given 

 volume of dry oxygen gas contained alone in an hermetically sealed 

 tube can be converted into ozone by the passage of electrical sparks, 

 is erroneous. In repeated trials, with tubes of every form and size, 

 the authors found that not more than j-J-^ part of the oxygen 

 could thus be changed into ozone. A greater effect was, it is true, 

 produced by the silent discharge between fine platina points ; but 

 this also had its limit. In order to carry on the process, it is neces- 

 sary to introduce into the apparatus some substance, such as a 

 solution of iodide of potassium, which has the property of taking 

 up, in the form of oxygen, the ozone as it is produced. After many 

 trials, an apparatus was contrived in the form of a double U, having 

 a solution of iodide of potassium in one end, and a column of frag- 

 ments of fused chloride of calcium interposed between this solution 

 and the part of the tube where the electrical discharge was passed. 

 The chloride of calcium allowed the ozone to pass, but arrested the 

 vapour of water ; so that, while the discharge always took place in 

 dry oxygen, the ozone was gradually absorbed. The experiment is 

 not yet finished, but already one-fourth of the gas in a tube of the 



