UNITED STATES DEPARTMENT OF AGRICULTURE 



M BULLETIN No. 449 ,, 



■S^'T^'^Kru 



Contribution from the States Relations Service 

 A. C. TRUE, Director 



J^^^'^^U 



Washington, D, C. 



PROFESSIONAL PAPER 



October 31, 1916 



A STUDY OF THE ELECTROLYTIC METHOD OF 

 SILVER CLEANING.^ 



By H. L. Lang and C. F. Waxton, Jr., Scientific Assistants, Offlce of Home 



Economics. 



CONTENTS. 



Page. 



Introduction 1 



Preliminary tests 3 



Principle of the electrolytic method 4 



Experimental study of the method 5 



A household method n 



Summary n 



INTRODUCTION. 



An understanding of the factors which influence the tarnishing 

 of metals and a knowledge of efficient methods for removing tarnish 

 are necessary for the proper care of household equipment. An ex- 

 tended study of these problems, therefore, is being made by the 

 Office of Home Economics, and the work reported in this paper is 

 a part of this investigation. 



The tarnishing of metals in general is due to the formation of 

 oxids or basic oxids of the metals by the chemical action of the 

 oxygen and water vapor of the air to which they are exposed. In 

 the light of recent investigations a distinction is made between 

 rusting, or oxidation, and the corrosion of metals. Thus, the rust- 

 ing of iron may be regarded as taking place in two steps: The dis- 

 pliicemeiit of the hydrogen ions of water with the formation of a 

 small amotint of soluble iron salts in the lower state of oxidation 

 is technically termed corrosion, while true rusting is the oxidation 



1 Preparnd \\n<]cr tlie direction of C. F. Langworthy, Chief, OfHcc of Home Economics. 



NoTK. — TlilH huljftln contalnH Informnllon rcuJirdinK (he jidvantdKcs and llmltnlions of 

 the i-lectrolytlc iTK-Hiofl of rN-anlnK Kilvir urid (Ik; (-((ndlt i(»ns under which It Is most 

 i-r!lcl<-nt, wlilch it Jh believed will prove uaeful to tcachcrH and Iious<;kceperH Kcuorully. 

 59849°— Bull, 449—10 



