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OXX. Viscosity of Air in a Transverse Electric Field. By 

 Satyendka Ray, M.Sc. Allahabad University, Research 

 Student, University College, London* . 



QUINCKE f found a change in the viscosity of liquids 

 in an electric field. Spheres of crown and flint glass 

 &c. 1 cm. in diameter were suspended by fine silk fibres 

 attached to the arms of a balance. The logarithmic decre- 

 ment was observed with and without a field due to 2000 

 volts, the distance between the plates being 1*5 cm. The 

 difference, which he calls electric viscosity, was 0"0398 in the 

 case of a crown glass sphere in liquid ether when the force 

 was transverse to the motion. Parallel to the lines of force 

 the viscosity also increases but to a smaller extent. 



Again in the case of gases the Faraday Mosotti theory of 

 dielectrics is very well satisfied as has been tested by Boltz- 

 mann ; and if poiarization physically means an orientation of 

 molecules or a kind of tidal distortion of the molecule, a 

 change in the effective area of the cross section and a 

 consequent change in the viscosity with the electric field 

 might be expected. 



To test whether there is any change in the case of gases 

 the transpiration method was employed. The usual capillary 

 tube was replaced by two steel plates 2 feet long, 2 inches 

 broad, and 1 inch thick. One face of each was planed and 

 these plane faces were placed parallel to and facing each 

 other. The plates were separated from each other by three 

 bits of drawn glass thread nearly 1 cm. long on which the 

 top plate was laid as on rollers. The sides were painted with 

 molten resin and wax, this method being found the best to 

 make the tube simultaneously electrically as well as pneum- 

 atically tight. The tube thus formed by parallel plates with 

 lateral walls was connected with the usual Mariotte's bottle 

 arrangement by means of a lin box fitted on one end of the 

 tube with wax and resin. Paraffin oil was used in the 

 Mariotte's bottle in the first instance, and the time of trans- 

 piration of a definite volume under constant pressure was 

 noted with and without the electric field. Latterly, however, 

 to eliminate complications arising from the use of paraffin 

 oil, dry air was sucked through instead. For this purpose a 

 second box was attached to the other end of the tube and 

 connected up with a sulphuric acid wash-bottle through 

 which the air was drawn in. The time for running out 



* Communicated by Prof. A. W. Porter, F.R.S. 

 t Quincke, Ann. d. Phys. u. Chem. lxii. (]897). 



