248 



Dr. G. Gore. On the 



[Dec. 16,. 



In order to arrange these solutions in a series, according to their 

 various degrees of electromotive force, a similar plan was adopted to 

 that employed when liquids of the same composition were used with 

 mercurial electrodes ; viz., two exactly similar apparatuses, with elec- 

 trodes of the same dimensions, were employed, one being charged 

 with one solution, and the other with the solution next to it in the 

 above series. The apparatuses were connected with the wires of the 

 differential galvanometer in such a manner that the two currents 

 passed through the two coils in opposite directions ; the direction and 

 amount of deflection being noted when the liquid in one vessel of each 

 apparatus was at 160° F. The series thus obtained is so arranged 

 that the couple giving the strongest positive current is at the top, and 

 that giving the most powerful negative current at the bottom, as in 

 the list already given. The solutions in which hot platinum was 

 positive are separated from those in which it was negative by a hori- 

 zontal line as in the above series. 



The positions of the solutions in the two series, although they agree 

 very closely, are not identical ; for instance, the two solutions of 

 formiate of sodium occupy respectively the seventh and tenth places 

 in the first series, and the third and eighth in the second series ; the 

 positions of a few other solutions are also changed, but not to so great 

 an extent. It will be observed that these two series agree more closely 

 than did those obtained with mercury, and this may, perhaps, be 

 accounted for by the fact that in these the superficial area of the 

 platinum electrodes was the same, whereas in the others the mercurial 

 surfaces were not equal in amount. 



Difference of amount 

 of deflection. 



1. Cyanide of potassium (120 grs.) 



2. Cyanide of potassium (60 grs.) . . . . .25 



3. Formiate of sodium (120 grs.) .25 



4. Carbonate of potassium _2^ 



5. Phosphate of ammonium 



6. Hyposulphite of sodium _2g 



7. Carbonate of sodium r ■ 



very slight 



8. Formiate of sodium (60 grs.) 2-q 



9. Sulphite of sodium (60 grs.) -^.q 



10. Sulphate of potassium -^q 



11. Sulphate of ammonium . „ V "hf 



12. Phosphate of sodium VG ^.25^ 



13. Borax 



14. Formic acid (96 minims) . . - - ^.q 



15. Cyanide of potassium (6 grs.) .^.^ 



16. Microcosmic salt (120 grs.) ^ 



17. Nitrate of potassium .. , , 



r very slight 



