340 BEPORT— 1888. 



Section last year, has appeared in the Physical Society's collection and 

 reprint of papers. 



The Committee may also call attention to a paper by Prof. Horace 

 Lamb, ' On the Theory of Electric Endosmose and Other Allied Pheno- 

 mena,' printed in extenso in the Manchester Volume, 1887, p. 495. 



Mr. Fitzpatrick's paper on Electrolytic Conductivity, communicated to 

 the Section last year, has been printed in the ' Philosophical Magazine ' 

 for November 1887. 



Bulletin No. 36 of the United States Geological Survey, ' On the 

 Subsidence of Fine Solid Particles in Liquids,' by Carl Barns, has been 

 sent from the Government printing-office at Washington to the Secretary. 

 It is interesting as containing an application of electrolysis to accelerate 

 the settling of turbidity ; and Dr. Gladstone's paper last year (1887 

 Report, p. 344), ' On the Action of an Electric Current in hastening the 

 Formation of Lagging Compounds,' may be mentioned in connection 

 with it. 



Dr. Arrhenius has transmitted to the Secretaries various reprints bear- 

 ing on the dissociation hypothesis of electrolytic conduction and other 

 matters, and one manuscript, which is appended to this Report. 



Dr. Richarz has also sent some papers, one of which, not being else- 

 where published, is annexed. 



The work of Prof. Rowland and Mr. Bell, ' On the Effect of a Magnet 

 on Chemical Action,' communicated verbally to the Section last year at 

 Manchester, has now appeared in the 'American Journal of Science ' for 

 July 1888, and in the ' Philosophical Magazine ' for August 1888. 



The Committee, at a previous meeting, instructed their Secretary to 

 endeavour to obtain the translation and publication of some of von 

 Helmholtz's papers. They have seen with great satisfaction that the 

 action of the Physical Society of London has rendered further motion on 

 their part in this direction unnecessary, and they congratulate Prof. 

 Carey Foster on the volume which has appeared under his supervision. 



The most remarkable experimental result within the scope of the 

 Committee to be recorded in the past year is that obtained by Dr. Hertz, 

 subsequently confirmed and further investigated by E. Wiedemann and 

 Ebert, Hallwachs, and Arrhenius, on the effect of ultra-violet light in 

 making air or any gas conducting, and especially in breaking down the 

 transition resistance or obstructive film at the cathode of an electric 

 sparking arrangement. The experiment is exceedingly easy to perform 

 with either a small induction coil or a Voss or Wimshurst machine, 

 the light used being either the light of another spark, or of magnesium 

 wire, or of an arc lamp. The length of a short spai'k may be trebled 

 by mere illumination with ultra-violet light : the difference of potential 

 between the terminals being kept constant. 



The fact that the effective cause of this phenomenon is not the long 

 waves of ordinary electric oscillation, but is the light which most nearly 

 corresponds in frequency to electric oscillation in bodies the size of 

 molecules, suggests some chemical or dissociation cause of the effect. 



Of the 50Z. grant made to the Committee la^?*^^ year, 30L has been 

 drawn and spent, partly in a rapid vibrator for the use of those experi- 

 menting on Ohm's law, partly in expenses connected with the preparation 

 of pure selenium, and the rest (some 151.) in separate copies, printing, 

 and postage. It is pi'oposed to ask for reappointment, with the sum 

 which has now lapsed renewed. 



