400 



DE. G. C. SIMPSON ON THE ELECTRICITY OF 



There is, however, in this result a slight error, due to the fact that when the 

 drops break up on the air jet a certain number of the fine drops produced are 

 carried upwards with the air stream and so escape out of the measuring system. This 

 loss was measured by the use of Simla tap water, which, as has already been 

 remarked, was found to be quite incapable of producing a charge, either by splashing 

 or breaking up 011 the jet. An experiment was made with tap water charged in the 

 same way as in the experiment just considered, and it was found that after breaking 

 on the jet the drops had lost part of the charge originally on them, both when the 

 charge was positive and when it was negative. The mean value of the loss was found 

 to be 5 per cent, of the charge on the drops. 



With drops originally uncharged a 5 per cent, loss was of no particular account, 

 the experiments were not accurate to this amount ; but with highly charged drops a 

 loss of 5 per cent, of the original charge was appreciable and had to be taken into 

 account. 



The following table gives the results of all the experiments made with charged 

 distilled water : 



TABLE XIII. 



From this table it will be seen that charged drops obtain a positive charge by being 

 broken up on the air jet, and that the magnitude of the charge is approximately the 

 same whether the drops are charged positively or negatively. Great accuracy cannot 

 be expected in these experiments with charged drops, because the electrometer has 

 to be made very insensitive in order to allow of the large charges brought down by 

 the drops being measured, and the final result is obtained from the slight variation in 

 these large charges caused by the splashing. It is, however, interesting to notice that 

 the mean of all the experiments with charged drops gives a mean charge due to. the 

 breaking up on the air jet almost equal to that found for uncharged water. 



In Table XIV the results of all the experiments are summed up : 



