276 Dr. G. Gore. Relations of Heat to Voltaic and 



Difference of strength of solution, like difference of temperature, 

 altered the order of the series with nearly every liquid. In the same 

 total number of instances (286), the number of reversals of position 

 in the orders, in liquids of four or five times the strength, was 74, 

 whilst that produced by a difference of temperature of 100 F. 

 was 83 ; therefore the usual amounts of chemico-electric molecular 

 change produced in the metals and liquids by these two causes were 

 not widely different. In twenty-nine cases the reversals produced by 

 increased strength of liquid, occurred with the same metals and 

 liquids as those produced by rise of temperature. Whilst also with the 

 286 members of the thermo-electric series in Table IV (see p. 260), a 

 variation of strength of liquid greatly altered the sequence, and 

 produced no less than 236 reversals, it caused only a moderate degree 

 of change of order, and only 74 reversals in the chemico-electric 

 series. This conspicuous difference between effects of increased 

 strength of liquid upon the thermo- and chemico-electric series, is 

 perhaps explicable by the circumstance that a thermo-electric couple, 

 consisting of an unequally heated metal and electrolyte, behaves like 

 a feeble voltaic combination of two metals and two liquids, and is a 

 more complex arrangement than a voltaic element of two metals and 

 one liquid, such as was used in forming the above Table XIII. 



The influence of strength of solution upon the electric potential 

 of the extreme top and bottom members of the " cold "columns of the 

 chemico-electric series of Table X, was also examined by the method 

 of balance; the liquids employed being the same as those used in 

 ascertaining the influence of the same condition upon the order of the 

 thermo-electric series of Table IV (p. 259). All the solutions were 

 used at 60* F. The results, placed side by side with those obtained 

 with the weaker liquids, are shown in Table XIV. 



Remarks. In twelve cases the electric potential was increased, 

 and in five decreased by increased strength of the solutions. The 

 total amount of increase was 3'55 times that of decrease, and the 

 average proportion of increase for the seventeen instances was '095 

 volt per 100 F. rise of temperature. The results when compared 

 with those in Table XI, p. 273, show that the increased strength of 

 the liquid had about the same average degree of effect as a rise of 

 temperature of 100 F. in increasing the chemico-electric potential. 

 The influence of increased strength of liquid upon chemico-electric 

 potential was different from that upon thei'mo-electric potential, in 

 the former it was usually attended by an increase, and in the latter 

 by a decrease, see Tables VI, VII. 



The electric potential of a voltaic couple appears to be in certain 

 cases decreased by rise of temperature (see Table XI, p. 273). This 

 circumstance is a consequence of the fact that by accession of heat 

 many metals become electro-negative, and others electro-positive in 





