1897.] and the formation of Clouds in Charged Gases. 255 



When / was connected with the electrometer one division of 

 the scale denoted "00405 electrostatic units of electricity, and 

 when D was connected each division denoted 00429 absolute 

 units. 



From these observations we get the electrification per c.c. and 

 the corresponding weight of cloud — it being assumed that the 



electricity passing from X to Y is Q 1 + -^ , 



Q x being the quantity of electricity that enters /, 

 Q 2 being the quantity of electricity left on D. 



18. Positively electrified oxygen and hydrogen were also sent 

 through this apparatus in order to be able to compare the dis- 

 charging powers, and it was found that for positive oxygen given 

 off by 14 amperes that the discharging power is "21, exactly the 

 same as in the case of negative oxygen when going at the same 

 rate, *85 c.c. per second. But in the case of the hydrogen the 

 discharging power was greater although it was going faster ; thus 

 when there were 11 "8 amperes going through the cell, the gas 

 going at the rate of 1*44 c.c. through the apparatus, the discharg- 

 ing power was '33 and with 13 amperes the discharging power 

 was '29. 



19. The second method that was adopted to find the weight 

 of the cloud was arranged with a view to ensure the complete 

 saturation of the gas, and the complete removal of the moisture 

 by bubbling through a set of three bulbs containing sulphuric acid, 

 and then weighing the latter. The sulphuric acid bulbs were 

 placed between P and Q and their discharging power found by 

 the methods already described while a current equal to that 

 which it is desirable to use to form the cloud is going through 

 the electrolyte, — the sulphuric acid having been removed from B 

 (fig. 3), and water substituted in its stead. In finding the dis- 

 charging power it is necessary to have the paraffin tunnel P 

 perfectly dry inside so as to ensure insulation, and this can be 

 relied upon for about 15 minutes while the moist gas is being 

 carried through P, but it was found that a considerable quantity 

 of moisture was left in P, and in the small tubes which were 

 embedded in the paraffin, so that an error would be introduced in 

 the weighing. If however the discharging power be first found P 

 can be removed and the sulphuric acid bulbs can be connected to 

 the tube leading from B which has a bulb blown on it so as to 

 prevent any spray being carried along it. The current should be 

 allowed to run for about three or four minutes before putting 

 on the bulbs to ensure that this delivery tube from B gets 

 thoroughly moistened. Having found the discharging power of 

 the bulbs it is now only necessary to observe the charge acquired 



