Dr. Faraday's Experimental Researches in Electricity, 171 



himself the observations of others without acknowledgement, 

 might have passed unnoticed by me for ever, had not the 

 friends of Mr. Bauer deemed this explanation necessary. 

 Primrose, January 31, 1835. 



XXIX. Experimental Researches in Electricity. — Eighth Se- 

 ries, By Michael Y arAdav, D.C,L.F,R.S.Fullerian Prof, 

 Chem, Royal Institution, Corr, Memh. Royal and Imp. Acadd, 

 of Scie?icesy Paris, Petersburgh, Florence, Copenhagen, Ber- 

 lin, Sjc, Sfc, 



[Continued from p. 1 33.] 



935. TN order to put the equal and similar action of acid and 

 '*• alkali to stronger proof, arrangements were made as in 

 (Plate I.) fig. 8.; the glass vessel A contained dilute sulphuric 

 acid, the corresponding glass vessel B solution of potassa, P P 

 was a plate of platina dipping into both solutions, and ZZ two 

 plates of amalgamated zinc connected with a delicate galvano- 

 meter. When these were plunged at the same time into the 

 two vessels, there was generally a first feeble effect, and that 

 in favour of the alkali, i.e. the electric current tended to pass 

 through the vessels in the direction of the arrow, being the 

 reverse direction of that which the acid in A would have pro- 

 duced alone : but the effect instantly ceased, and the action 

 of the plates in the vessels was so equal, that, being contrary, 

 because of the contrary position of the plates, no permanent 

 current resulted. 



936. Occasionally a zinc plate was substituted for the plate 

 P P, and platina plates for the plates Z Z ; but this caused no 

 difference in the results: nor did a further change of the mid- 

 dle plate to copper produce any alteration. 



937. As the opposition of electro-motive pairs of plates pro- 

 duces results other than those due to the mere difference of 

 their independent actions (1011. 1045.), I devised another 

 form of apparatus, in which the action of acid and alkali might 

 be more directly compared. A cylindrical glass cup, about 

 two inches deep within, an inch in internal diameter, and at 

 least a quarter of an inch in thickness, was cut down the mid- 

 dle into two halves, fig. 9. A broad brass ring, larger in di- 

 ameter than the cup, was supplied with a screw at one side ; 

 so that when the two halves of the cup were within the ring, 

 and the screw was made to press tightly against the glass, the 

 cup held any fluid put into it. Bibulous paper of different 

 degrees of permeability w^as then cut into pieces of such a size 

 as to be easily introduced between the loosened halves of the 



Z2 



