and its relation to Ozone. 57 



In this experiment, as well as in the others, the current produced 

 by six carbon and zinc elements renewed twice daily, was regu- 

 lated by means of an interposed tangent galvanometer. The abso- 

 lute intensity of the current, reduced to Gauss's standard, varied 

 during a week's experiments between 10*6 and 21*8. With this 

 the gas passing through the apparatus moved sufficiently slowly 

 to become completely dried. 



After these remarks, I may turn to the analysis itself. 



As has already been mentioned, ozone acts in such a manner 

 upon the solution of iodide of potassium, that the oxygen which 

 is combined with the elements of water to form ozone sets free 

 its equivalent of iodine, whilst caustic potash is formed. In con- 

 sequence of this, the solution of iodide of potassium is seen to 

 acquire a brown colour after a short time. This colour, however, 

 disappears again soon, in consequence of the separated iodine 

 acting again upon the potash which has been formed, causing the 

 formation of iodate of potash and iodide of potassium. After the 

 electrolytic oxygen has been passed through for some time, a cry- 

 stalline coating of separated iodate of potash, mixed with iodide 

 of potassium, appears on those parts of the apparatus which have 

 become dry. If muriatic acid be added to such a solution, 

 which contains free iodine as well as iodate of potash and iodide 

 of potassium, the iodine of the iodate of potash is completely 

 separated, with formation of water, as shown by the following 

 experiments. 



9*2808 grms. of pure dry iodine were weighed between two 

 watch-glasses and dissolved in solution of iodide of potassium. 

 The hundredth part of this solution, which consequently con- 

 tained 0*092808 of iodine, was mixed with caustic potash until 

 the disappearance of the brown colour, and then with muriatic 

 acid until its reappearance. A certain quantity of sulphurous 

 acid added to this solution required for its perfect destruction 

 at' = 0*0214 of iodine. The same quantity of sulphurous acid 

 by itself required 0/= 0*1 134 of iodine. The quantity of iodine 

 found consequently amounted to 0*092, which only differs from 

 the quantity employed by about T 8 <jths of a milligramme. In a 

 second experiment at' = 0*0209 of iodine was obtained, which 

 corresponds with 0*0925 grm. of iodine, and consequently shows 

 a difference of only y^ths of a milligramme. As the only inten- 

 tion of these experiments was to prove the complete decomposi- 

 tion of iodate of potash by iodide of potassium in the presence 

 of muriatic acid, I bestowed no particular care upon the accuracy 

 of this quantitative determination. If the fluid be measured 

 more exactly, or still further diluted, the chance of error will be 

 confined within equally narrow limits, as in the preceding expe- 

 riments. The error may then be reduced to only the hundredth 

 of a milligramme. 



