372 Mr. T. Andrews. Action of Tidal Streams on [June 18,. 



June 18, 1885. 



THE PRESIDENT in the Chair. 



The Presents received were laid on the table, and thanks ordered 

 for them. 



Sir Andrew Clark, Bart., Dr. Francis R. Japp, Dr. Arthur Milnes 

 Marshall, and Mr. "William Mitchinson Hicks were admitted into the 

 Society. 



The following Papers were read : — 



I. "The Action of Tidal Streams on Metals during Diffusion 

 of Salt and Fresh Water. Experimental Research. 

 Part II (Gravimetric)." By Thomas Andrews, F.R.S.E., 

 Wortley Iron Works, near Sheffield. Communicated by 

 Professor G. G. Stokes, Sec. R.S. Received May 29 y 

 1885. 



In a paper last session " On the Electromotive Force during Dif- 

 fusion in Tidal Streams " (see " Proceedings Royal Society," No. 232),. 

 the author recorded the electrical part of this investigation. The 

 present communication contains the concluding gravimetric experi- 

 ments of the research. The effects attending the diffusion of the salt 

 and fresh water in tidal estuaries, on parts of the same metal, were 

 estimated in each case for a period of one year, during which the 

 metals were constantly exposed to conditions of galvanic action 

 similar to those obtaining in some tidal streams. The results 

 demonstrate that electric disintegration of the nature alluded to 

 in this and the former paper (viz., the galvanic destructive action 

 on parts of even the same metal, arising from difference of potential 

 during diffusion between the surface and lower waters in a tidal 

 stream) is, on comparison with other investigations by the author, 

 apparently of much greater extent than the loss either from simple 

 corrosion in sea water alone, or than that which ensues from the 

 action on each other of dissimilar metals of this group (such as 

 wrought iron, cast metals and steels) in galvanic connexion in sea 

 water. The wrought iron, steels, and cast metals used were from 

 the author's standard samples of known composition in the form of 



