•1883.] 



Action of Metals in Electrolytes. 



51 



The potentials of voltaic currents with the same series of metals in 

 the weak solutions at 60° F. were also determined in seventy-five 

 instances, in each case in thermo-electric terms of one of the same 

 metals in the same liquid ; and the number of degrees of difference of 

 temperature of the particular thermo-electric couple required to 

 balance the corresponding voltaic couple in each instance is given in 

 a table. 



A series of experiments was also made to determine whether the 

 difference in potential, caused by heating a voltaic couple, is com- 

 pletely accounted for by the electromotive forces produced by the 

 same rise of temperature of the same metals separately in the same 

 liquids, and the results are shown in a table. 



With considerable difficulty, a series of about 120 determinations 

 were also made of rates of ordinary chemical corrosion of the same 

 metals in solutions of the same substances at 60° F., and a second 

 series of about seventy-five determinations with the same metals and 

 liquids at 160° F. were also made, and the results are given in two 

 tables. 



These and other results are contained in a series of twenty tables; 

 and by comparing the contents of these various tables with each other, 

 and also by means of additional experiments, a number of general 

 eonclusions were obtained. The following are the conclusions, and 

 the chief results arrived at by these means. 



It is shown that when metals in liquids were heated, they were 

 more frequently rendered positive than negative in the pr oportion of 

 about 2*8 to 1 ; and that while the proportion in weak solutions was 

 about 2*29 to 1, in strong ones it was about 3'27 to 1 ; and this 

 accords with their thermo-electric behaviour as metals alone. The 

 thermo-electric order of metals in liquids was, with nearly every 

 solution, whether weak or strong, widely different from the thermo- 

 electric order of the same metals alone. A conclusion previously 

 arrived at was also confirmed, viz., that the liquids in which the hot 

 metal was thermo-electro-positive in the largest proportion of cases, 

 were those containing highly electro-positive bases, such as the alkali 

 metals. The thermo-electric effect of gradually heating a metal in a 

 liquid was sometimes different from that of suddenly heating it, and 

 was occasionally attended by a reversal of the current. 



Degree of strength of liquid greatly affected the thermo-electric 

 order of the metals. Increase of strength usually and considerably 

 increased the thermo-electric potential of metals thermo-electro- 

 negative in liquids, and somewhat decreased that of those positive in 

 liquids. The electric potential of metals thermo-electro-positive in 

 weak liquids was usually about 3'87 times, and in strong ones 1*8 7 

 times as great as of those which were negative. The potential of fch e 

 strongest thermo-elestric couple, viz., that of aluminium in weak 



E 2 



