1897.] and the formation of Clouds in Charged Gases. 251 



These numbers give accurately the effect, on the discharging 

 power due to the presence of a cloud, as no change was made in D 



while water was being substituted for sulphuric acid in H'. In 

 order that the relative discharging powers of sulphuric acid, water 

 and KI solution should be obtained to the same accuracy, the 

 depth to which the tube in H dips into the liquid should be very 

 accurately adjusted. But seeing that in these experiments a 

 large part of the discharging power is due to the glass wool no 

 particular precautions were taken to ensure this, but the tube 

 was dipped under the liquids in each case to equal depths as 

 accurately as the eye could judge. 



13. The above numbers were obtained from experiments with 

 negative oxygen, and as far as they and several similar experiments 

 show, there is no increase, but rather a diminution in the dis- 

 charging power of D, both in the case of positive and negative 

 oxygen, when potassium iodide solution is substituted for sul- 

 phuric acid or water in H. So that the question of the ozone 

 being the carrier of electricity is inadmissible, as is also the 

 suggestion that the cloud consists of hydrogen peroxide, for not 

 only is the charge not removed by being sent through the 

 potassium iodide solution, but when the dry gas is led into this 

 solution the cloud appears in the space in H above the solution. 



14. When we consider the first series of numbers, which show 

 that the removal of the cloud by sulphuric acid does not discharge 

 the gas even to the same extent as bubbling the dry gas through 

 the same acid, it might at first sight appear that the cloud and 

 the charge had nothing to do with one another. It must however 

 be remembered that only a very few of the drops forming the 

 cloud come into contact with the acid, and the disappearance of 

 the greater number of the drops is due to evaporation caused by 

 the lowering of the vapour pressure by the sulphuric acid, and we 

 have thus a good example of vapour coming off a charged sphere 

 without carrying with it any of the charge. (See J. J. Thomson, 

 Recent Researches in Electricity and Magnetism, page 54.) 



15. This evidence showing that the carriers of the electricity 



VOL. IX. PT. V. 



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