Electricity of Drops. 



345 



When the vessel was filled with hydrogen, the electrification 

 of the drops was reversed : the drops, after striking against 

 the plate, being negatively electrified, while there was a posi- 

 tive charge distributed through the hydrogen. Lenard found 

 that the effect was considerably less in hydrogen than in air. 

 If care is taken to get rid of all traces of air, the effect is not 

 merely diminished but reversed. 



This and the experiment previously described seem to indi- 

 cate that the effect is due to chemical action. This view is 

 confirmed by the very large effects produced by the addition 

 of small quantities of various foreign substances to the water 

 forming the drops. 



The results of experiments made upon a considerable variety 

 of substances are given below. In each case the deflexion 

 given is that produced when 100 cubic centim. of the sub- 

 stance fall through the funnel. The deflexion is marked + 

 when it is in the same direction as that due to pure water 



ailing 



through air. 





















Hydrochloric Acid. 











Strength of 

 Solution. 





Deflexion. 





Strength of 

 Solution. 



Deflexion 



Pure water 





125 + 



1 100 + 



•2 c. c. of HOI made up 

 to 100 c. c. with H 2 

 •4 



~ 55 55 55 



} 





•2 c. 

 c 



c. of HC1 ir 

 . c. of H 2 



L 10" 





 



•4 



>j jj 



» 



65 + 



•8 



55 



55 55 





2- 



•8 



>j j> 



li 



45 + 



1-6 



55 



55 55 





3- 



1-6 



>» » 



55 



12 + 



3-2 



55 



55 55 









32 



" )> 



55 



3+ 



6-4 



55 



5) 55 





2- 



64 



» >> 



>> 







12-8 



55 



55 55 









12-8 



» j> 



55 







25-0 



55 



55 55 









250 



55 55 



55 







50-0 



55 



5) 55 









500 



55 55 



>> 

















In this case any addition of the substance diminishes the 

 electrical effect, and only requires a small quantity of HC1 to 

 make the solution neutral. When the solution has become 

 neutral it remains so in spite of the addition of more acid. 

 We shall see that other substances, such as zinc chloride, 

 oxalic acid, &c, show the same peculiarity. 



Strength of 

 Solution. 



Water 180 + 



•2c.c. ofH 2 SO 4 ml000~l An 

 e.c. ofH 2 J * U ~ 



I 55 55 55 )S 30 



1*0 „ ,, ,, „ "0 — 



*■' i 55 55 55 55 ^O 



3'0 „ „ • „ ,, 30 — 

 60 „ „ „ „ 30- 



Sulphuric Acid. 

 Deflexion. 



Strength of 

 Solution. 



1 c. c. of H 2 S0 4 made up 



to 100 with H o ... 



«-* 55 55 55 5J 



tO ,, ,) 5) 55 



■i\j << .1 15 55 



Deflexion. 



} 10 - 



5- 

 10- 

 10- 



