THE ELECTROLYTIC METHOD OF CLEANING SILVER. 



T.u?LE I. — Comparaiirc efficiency of solutions of loashing and baking soda at 

 the hoiUny temperature— Continued. 



Solution. 



Time required for 

 cleaning. 



Remarks. 





Ohserved. 



Average. 





Series 9. 



■Washing soda 



Do 



Seconds. 

 5 

 4 



2.5 

 4 

 4 

 5.5 



4 

 3 

 2 

 2 

 3 

 3 



a 



4 



5 



3 



3.5 



4.5 



3 

 5 

 6 



5 



7 

 11 



Seconds. 



} ' 



1 ' 



1 - 



1 » 



1 ^ 

 1 



1 = 

 1 ' 



IThe aluminum used in series 9 liad been cleaned by polishiiis 

 \ with emery cloth. 



Do 



Baking soda 



Do 





Do 





Series 10. 



Washing soda 



Do 



(In series 10, 11, and 12 the active metal used'was zinc. In series 



Do 



[ water. 



Bakingsoda 



Do 





Do 





Series 11. 



"Washing soda 



Do 



The zinc was not cleaned with acid in series 11. 



Do 





Bakingsoda 



Do 





Do 





Series 12. 



Washing soda 



Do 



(The zinc had been standing in the hot cleaning solution for 10 

 \ minutes before use in series 12 and was not cleaned with acid. 



Do 



Bakingsoda 



Do 





Do 









From the results of these experiments it is evident that washing 

 soda is slightly more efficient than baking soda, the average time re- 

 quired, considering all of the tests, being 9-i seconds for the washing- 

 soda solution and 10^ seconds for the baking-soda solution. For all 

 practical purposes, since the difference between the efficiency of wash- 

 ing soda and that of baking soda is so small as to be within the limits 

 of experimental error, it may be considered feasible to use them in- 

 terchangeably. As far as the appearance of the cleaned spoons was 

 concerned, no difference was noted in the two solutions; all the spoons 

 that were cleaned showed a briglit satin finish after each cleaning and 

 were practically as bright at the end of each experiment as at the 

 start. Wasbing soda is somewhat more economical, since it is more 

 efficient and cheaper as well. 



The next factor to be considered was the effect of increasing the 

 coruliictivity of tlie <^'l('aniiig solution, and common salt was used for 

 tills pijr])ose. In the following experiments the silver to be cleaned 

 was uniformly tarnished by immersing the spoons in the same tarn- 

 ishing solution f(jr the same lenglli of time. Tn .some of the tests aln- 



