ELECTRIFICATION OF AIR, VAPOUR OF WATER, AND OTHER GASES. 203 



through a small vertical slit in the paraffin stopper. The electrometer shows positive 

 electricity, which proves the withdrawn air to have been negatively electrified. 



42. Very many experiments were made to test the effect of shaking up the air 

 in the bottle with solutions of different substances, the solutions being varied from 

 saturated (100 per cent.) down to practically pure water. For this purpose three 

 acids (sulphuric, hydrochloric, and acetic), three alkalies (sodium hydrate, lime, and 

 ammonia), and three salts (sodium chloride, sodium carbonate, and zinc sulphate), 

 were used. 



Curves 4, 5, 6. 

 o-e 



43. Curves 1 to 9 show the results obtained. Generally, each test was repeated 

 a large number of times, and the curves are drawn for mean values. It will be 

 noticed that, with the exception of lime water, all the acids, alkalies, and salts, when 

 added to the water in the bottle in very minute quantities, showed a rapid diminution 

 in the negative electrification of the air produced by shaking it up with the liquid. 

 In some cases a single drop of a saturated solution of the substance added to the 

 water and shaken up with the air was almost enough to entirely neutralize the 

 negative electrification of the air which is obtained by shaking up with pure water. 

 On gradually increasing the strength of any of the solutions named, the zero line is 



2 D 2 



