631 



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 the amount in all of nearly three-fourths, is recovered. 



As an illustration of the economic importance of this material in 

 applied 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 56216* 



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; 10 yards No. 16 wire. 



