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llEPORT — 1884. 



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moivury of tlio Clark Cfll. No inereiirous 8iilplmt(! is einploye:!, tho liquid ]mn^r 

 simply 11 siitiinitcd suliition ol" zinc siilpliad'. 



if till! sniun kind of iimalj:ani !)•■ u.scil Cor liotli poles, lln'symmi'tiy is coni]ilctc, 

 and th(!ri! alioild Lc no K. M. F. JJiit it' \v(^ take lor ono jiolo a istidnfj-, Imt lluid, 

 ninal},'am, and ibr Iho otiicr tho same anial^'am diliilcd witli an «'f|inii vohiino of 

 pure nierciiry, wi' find a very sensibli! V). M. 1''., tiit; sIimii^' amalgam corrcsiinndiii;: 

 lo tiu' zinc of tlio ordinary (.'lark. In my ('X])erimi'nt Ibe ]•]. M. F. was •()()! ('jiirli, 

 and remained ])retly constant from day to day. In anotlier cidl the .siinit' sinm;: 

 amalf^am was used for ono polo, and for tlie other poh^ was diluted wit h tlirec times 

 its volume of ]»uro mercury. In this case the E. Al. F. was "UOO (Uarli. 



if wo rejdace the diluted araalj,'am with pure mercury, we obtain (witlioul 

 morcurous suijdiate) nearly tln^ full I'l. M. F. of the Clark cell, but, as nii^dit be 

 expected, tlie lorce is very unsteady. From this it would seem that the function (jI' 

 the mercmrons sulphate in tho usual Ibrm of ctdl is to retain the jmriiy nf the 

 niercurv, and that tiio J'i. .M. F. is largely duo to the allinity of inercury for 

 zinc. 



4. On an Analogy between Heat and FAcdi-li'itij. 

 Bij Professor G. F. Fitzgeuald, F.U.H. 



Tho object of this communication was to point out the analojjry that mny lio 

 drawn lietween ([uantity of electricity and quantity of entropy wdien electrii 

 potential is considered as analo{rous to temperature. A non-conductor of electricity 

 would bo a non-conductor of entropy, which is the same as a non-conductor of 

 heat. A conductor would bo a heat engine in which the fall of temperature of the 

 entropy was complettdy utilised. 



It was ])oiutod out that a molecidar structnro of tho ether could bo assumrd 

 ■which woidd not conduct heat as material gases do, but wdiich might be tin-own by 

 diireronces of temi)eraturo into tlie .state of .stress that explains electrostatic pheno- 

 mena. It was exjdainoil that tliis was a stej) beyond that made by .Maxwell in his 

 Floctricity and jMagnetism, where ho avoids any hypothesis as to how electric 

 displacement produces mechanical stress. It was, on tlio other hand, e\]ilained 

 that the priiici])al object of tho paper was not to bring i'oi'wnrd this very doubtful 

 hypothesis, but to point out that the analogy of electric currents and displacements 

 to the motion of an incompressible fluid was by no mer.ns the only one that could 

 be drawn, and by pointing this out, to obviate the danger ■wdiich is at present 

 imminent of this mere analoyrv beinj' considered as a likeness. 



5. Tlie Telemeter Si/stem. By J. Urquuaim' Mackenzie. 



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C). The Injhirnce nf an Electric dirreul on the Thinulinj of a Li'/ni'l FlUn. 

 By Professors A. W. Reixold anj, A. W. RCoKEit. 



The authors described the effect of passing a current of from O'o to lo micro- 

 amperes through a cylindrical liquid lilm. The films were about 40 mm. long and 

 .'3'J mm. in diameter, and were formed of a solution either of common potash soa|i, 

 or of Plateau's * liqnido glycerique,' •with a small quantity of nitratt; of ])otash added 

 ■ to improve the conductivity. A number of films wore formed, and allowed to thin 

 under the action of gravity alone, when no current flowed. They all behaved 

 substantially in tho same way. After a few minutes signs of colour wore seen at 

 the top, and in from !) to IT) minutes a complete ring of black appeared. Three 

 quarters of the film were colourless. When a downward current was passed 

 through a film from the moment of its formation, rings of colour appeared with 

 great rapidity, but much broader and more diffuse than before, and occu])ying a 

 larger area of the liquid. If the film had already a ring of black at the top, the 

 effect of the downward current ■was to augment this, and rapidly {o thin the 

 portion immediately below it. In all cases, provided the current was not too 



