132 ' On Ozone. 



probable formula ; but it has since been shown by Dr. 

 Andrews (see his paper on Ozone in Philosojohic Transactions, 

 Vol. 146, Part I.) that hydrogen cannot form part of it. 

 He sums up his elaborate researches with these words : — 

 " Ozone, from whatever source derived, is one and the same 

 body, having identical properties and the same constitution, 

 and is not a compound body, but oxygen in an altered or 

 allotropic condition." This view of the natui^e of ozone is 

 the one, I believe, now generally adopted. 



According to Dr. Apjohn, " Ozone is a gas of a peculiar 

 odour, hence its name (o^w, / smell) having some resemblance 

 to that of chlorine, diluted with much atmospheric air." 

 Its specific gravity, according to Tait and Andrews, is four 

 times that of oxygen, or taking air as I'OOO, it is 4*4224. It 

 possesses the greatest oxydating power of any known body, 

 as at ordinary temperatures it destroys vegetable colours, 

 corrodes organic structures, and powerfully oxydizes most 

 metals. Like all other active oxydating agents, it decomposes 

 iodide of potassium, and sets the iodine free, and this fact is 

 used for the ordinary test for the presence of ozone. Free 

 iodine dyes starch an intense blue ; therefore, strips of 

 chemically pure paper, dipped in a mixed solution of 

 iodide of potassium and starch and dried, v/hen exposed to 

 ozone and then moistened, turn blue, with a gTeater or less 

 intensity, according to the quantity present. Although this 

 test is liable to similar reactions with several other sub- 

 stances, it has been found the most useful and certain, and is 

 generally adopted. 



Ozone can be produced artificially in many ways : by 

 passing sparks of electricity through atmospheric air, or 

 better through oxygen ; in the decomposition of certain 

 aqueous solutions by electrolysis ; by the slow oxydation of 

 phosphorus, ether, turpentine, &c., at common temperatures 

 in atmospheric air ; and by decomposition of permanganate 

 of potash. The peculiar odour observed during electric 

 discharges, especially of frictional electricity, is due to the 

 ozone evolved. For experimental purpose the phosphorous 

 and permanganate of potash modes are generally adopted. 

 The evaporation and consequent oxidation of ether, however, 

 appears, both from experiments of my own, and from a long 

 series of observations of my friend, Dr. John Day, of Geelong, 

 to be a very convenient method of ozonizing air. The effect 

 of ozone, or ozonized air, on animal life, has formed the 

 subject of investigation by many chemists and physiologists. 



