Mr. C. V. Walker on Platinized Grwphite Batkries. 73 

 Approximate Formulce. 



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III applying the exact formulae, the relations between p, v, and t 

 may be found by means of known formulae or Tables- 

 February 3. — Sir Benjamin C. Brodie, Bart., President, in the Chair. 



The following communication was read : — 



"On Platinized Graphite Batteries." By C.V.Walker, Esq., 

 F.R.S., F.R.A.S., &c. 



In a short note communicated to the Royal Society on March 

 9th, 1857, and which was read on March 19th, reference was made 

 to the voltaic combination that I had adopted for certain telegraphic 

 purposes ; namely, zinc-graphite. Graphite in its crude state had 

 for some years been of great service to me, especially for batteries 

 whose resting time is great in proportion to their working time. 

 Since the date of that notice, I have considerably increased the value 

 of graphite for electrical purposes by platinizing it according to the 

 process first described by Mr. Smee, whose platmized silver battery 

 has been long known and much used. The material to which I 

 refer by the term " Graphite," is the crust or corrosion that is col- 

 lected from the interior of iron gas retorts that have been long in use. 



My first crude graphite battery of twelve pairs of plates was set 

 up on April 5th, 1849, for working the telegraph from my residence 

 at Tonbridge to the Telegraph Office about a mile distant. It was 

 charged with sand saturated with diluted acid ; and had not been dis- 

 mounted in March 1851, when I changed my abode. During the 

 interval, the sand was from time to time moistened with acid water or 

 water only. The plates in this case had been roughly chipped out and 

 rubbed on stone into something like shape. In the mean time I 

 had some sets of plates cut at the Locomotive Works, Ashford, and 

 was thus enabled to obtain further results. I forwarded a graphite 

 battery to the Great Exhibition in 1851, for which a prize medal 

 was awarded. The introduction of graphite into anything like 

 general use was for a long period no easy matter, on account of the 

 difficulty of finding any one who would undertake to cut it into 

 plates, its hardness destroying the tools ; and the then limited de- 

 mand did not encourage any one to construct special machinery for 

 the purpose. My wants at length reached the ear of Mr. J. Robin- 

 son of Everton, Liverpool, who took the matter thoroughly in hand, 

 and has succeeded perfectly in cutting plates into any form and to 

 comparatively any size, at a very moderate cost, for which I am much 

 indebted to liim. I have before me plates 12 inches X 10 inches, 

 of smooth texture and uniform tliickuess, and have seen some of 

 double tliat size. 



The plates in common use for bell signals arc 7 J inches X 3 inches 



