M. Soret on Ozone. 209 



My first idea was to try and ascertain whether less or more ozone 

 was produced in light than in darkness. I found no appre- 

 ciable difference, but I found that, with the voltameter which I 

 used, I produced even at ordinary temperatures very considerable 

 proportions of ozone. I worked with a voltameter of 500 to 

 700 cubic centims. capacity, filled with acidulated water (one 

 volume of SO 3 HO to five volumes of water), with very fine wires 

 of platinum-iridium for electrodes ; the negative electrode was 

 surrounded by a porous cell, and the gases were consequently 

 not mixed. I obtained at ordinary temperatures, much higher 

 than that of 0°, a quantity of ozone varying with the circum- 

 stances, but amounting almost to 1 per cent, for the whole of 

 the oxygen disengaged. The gas appeared to be capable of 

 being dried by passing through sulphuric acid without appreci- 

 able loss of ozone. By surrounding the voltameter with a mix- 

 ture of ice and salt, and allowing the oxygen to pass directly 

 into iodide of potassium, I obtained a quantity of iodine corre- 

 sponding to 20 milligrammes of oxygen ; the oxygen collected, 

 after passing through the iodide, filled a flask of 720 cubic cen- 

 tims. capacity. If, then, we assume that the 20 milligrammes of 



oxygen absorbed represent ozone,, we obtain a proportion of — r . 



J vJO 



By collecting the gas under water, and absorbing with iodide of 

 potassium after all the gas has been disengaged, less oxygen is 

 found, because water dissolves a considerable proportion (about 

 one-fifth of the ozone liberated in an experiment in which the 

 water was analysed). 



These proportions are then very appreciable ; and the essential 

 conditions for obtaining them appear to be — 



1. The use of large voltameters, to avoid the heating by the 

 passage of the current, and perhaps a perturbing action of the 

 oxygenized water. 



2. The separation of the gases. 



3. The use of electrodes of platinum-iridium exercises possibly 

 also an influence. 



4. The cooling of the voltameter. 



5. The use of a sufficiently concentrated solution of sulphuric 

 acid. 



I availed myself of the facility of the production of ozone to 

 repeat Baumert's fundamental experiment, in which dried elec- 

 trolytic oxygen, passed into a glass tube coated with a slight 

 layer of anhydrous phosphoric acid, dissolves this deposit if the 

 tube has been heated at one point — an experiment which, accord- 

 ing to Baumert, proves that ozone contains hydrogen. In 

 operating with a voltameter in which the two gases were disen- 

 gaged (they were separated by a porous cell), I found' in fact 



Phil. Mag. S. 4. Vol. 25. No. 167. March 18G3. P 



