70 Mr. C. Binks on Electricity, 



continued use, and deteriorated by the sulphate of zinc dis- 

 solved in it ; so that the results of any set of comparative ex- 

 periments will be untrue, unless this source of variation and 

 error shall have been completely avoided by the constant re- 

 newal of the acid, or completely provided against by some 

 system of correction adapted to its varied effects. 



54-. XIV. A voltaic arrangement, at the commencement of 

 a set of experiments, when the apartment in which they were 

 conducted was comparatively of a low temperature, viz. at 

 53° Fahr., gave j^^^ of a cubic inch of hydrogen in 45 se- 

 conds. But on the room becoming warmer, by means of the 

 fire and lights used in it, the action of the arrangement was 

 as progressively increased, and when arrived at the tempera- 

 ture of 60° the same measure of gas was produced in 30 se- 

 conds. Attempts were made to alter this activity of the ar- 

 rangement by altering the surface of the zinc, by re-amalga- 

 mating it and immersing the plates in cold water, but without 

 effect; and the original amount of action was restored only 

 after a free admission into the room of a current of a colder 

 atmosphere, during a few hours, had reduced it to the original 

 temperature. It is worthy of remark here, that whilst the 

 atmosphere in the apartment suffered a change equal to 7 de- 

 grees of temperature, the liquid the plates were acting in did 

 not alter by more than two degrees ; and I have since had 

 occasion constantly to observe that the changes in question, 

 induced by temperature, in the activity of the arrangements, 

 may be brought about equally when the surrounding atmo- 

 sphere alone (that is, independently of any alteration in the 

 temperature of the plates or the liquid) is the body which has 

 undergone any perceptible change. 



B5. These effects of the influence of atmospheric tempera- 

 ture, though ascertained by a different method and independ- 

 ently, are in exact accordance, in general character, with 

 those detailed by yourself, and respecting which you remark 

 that " it is now, however, apparent that in the exact measures 

 of different effects which an invariable current of electricity 

 will enable experimentalists to undertake, the variations of 

 atmospheric temperature even must not be neglected*." 



56. XV. There is yet another influence affecting the action 

 of voltaic arrangements which has not, that I am aware of, 

 been previously recognised; namely, the mechanical effects 

 of the pressure of the column of liquid resting upon the plates. 

 If in a trough, holding dilute acid and about 12 inches deep, 

 a small zinc plate be fixed at half its depth or at 6 inches, 

 and the associated copper plate of the same size be fixed, first 



* Philosophical Transactions, 1837. 



