Mr. C. V. Walker on Platinised Gi-aphite Batteries. 75 



the jars are filled up as occasion requires. The greater portion of the 

 mercury is recovered : when old plates come home, a considerable 

 quantity of rich amalgam is scraped from the plates ; this is placed 

 in jars of acid water, and a few pieces of graphite are thrown in ; the 

 electro-chemical action makes the amalgam poorer of zinc, and mer- 

 cury is easily expressed. By continuing the operation, more mer- 

 cury, to theamount in all of nearly three-fourths, is recovered. 



As an illustration of the economic importance of this material in 

 apphed science, I am informed that the silver plates of the batteries 

 constructed for the Atlantic Telegraph cost ^62520 or more. On my 

 having directed the attention of the Company to graphite as a sub- 

 stitute for silver, a set of plates were ordered, equal in number and 

 size, which were supplied (furnished with electrotype copper and 

 connecting wires) for a6216. 



The following Table illustrates the effective working powers of 

 platinized graphite, as compared, under like circumstances, with pla- 

 tinized silver, given in lifting powers in pounds. A third column is 

 added, giving the results when table salt is dissolved in the water 

 employed with the graphites. 



Table I. 

 Electro-magnet ; lo yards No. 16 wire. 



