86 



Prof. G. Quincke on Electrical Expansion. 



for some time, and the increase of volume persists for the 

 same length of time ; it then disappears gradually. With 

 better conductors (as glycerine, alcohol, and water) the level 

 rises almost instantly, and the battery is discharged imme- 

 diately. 



The same quantity of negative or positive electricity in the 

 Leyden battery gives nearly the same change of volume of 

 the liquid. The change of volume is nearly proportional to 



— when q denotes the quantity of electricity and s the 



charged surface of the Leyden jar. 



31. With fluids which insulate well, the electrodes may be 

 connected with a Holtz's machine instead of a Leyden battery. 



32. With fatty oils which insulate well, a decrease of 

 volume takes place instead of an increase. 



33. When the electric charge is too great, a spark passes 

 in the fluid between the platinum electrodes, and the volta- 

 meter is broken. Hence the different liquids could not be 

 examined in the same apparatus. 



The following table gives an approximate comparison of 

 electric dilatation with thermic dilatation, the expansion being 

 multiplied by 1,000,000. The electric expansion is that of a 

 layer of substance about 12 millims, in thickness, acted on by 

 the electricity. 



Expansion — X 10 e . 



By increase of 



temperature 



from0°C.tol o C. 



By a quantity of elec- 

 tricity. 



+20 



+40 



Carbon disulphide 



Alcohol 



Petroleum 



Turpentine 



Glycerine 



Distilled water at 8° C 



Water with a trace of hydro 



chloric acid at 10° C 



Water with 0124 % hydrochloric 



acid at 13° 



Distilled water at 0° 



Water at 0° with a trace of hydro 



chloric acid 



Water with 0424 % hydrochloric 



acid at 0° 



Thuringian glass 



Flint glass 



CoLza oil 



Almond oil 



1141 



1042 



1017 



902 



512 



92 



-20 



32 



26 



773 



775 



5-23 

 6-80 

 5-66 

 1-70 

 0-59 

 0-07 



013 



0-07 

 -003 



-0-06 



-0-03 

 0-003 

 0002 

 -18-24 

 -6*85 



22-43 

 3550 



42-45 

 3-19 

 0-23 



0-42 



0-56 

 -0-09 



-0-30 



-0-36 

 0-010 

 0-009 



