''iiwliliiiiiHiii-ii>''';,,i,,||;,il4!iii'ii:i!ii;|!!: 



iiliiiiiiili^^ 



Fig. 12. 



Figure 24. — Battery of Smee cells as used in American telegraphy. From 

 G. F. Prescott, History, Theory, and Practice of the Electric Telegraph, Boston, 

 i860, p. 33. 



the Clark cell entirely. One of the earliest Weston 

 cells used by the National Bureau of Standards is 

 shown in figure 38. 



ELECTROCHEMISTRY 



Almost as soon as a source of electrical current was 

 invented by Volta, the chemical effects of this current 

 were noticed. Among the first to remark these effects 

 were Nicholson and Carlisle, in 1800.''' They used a 



drop of water on the top of their pile to ensure a good 

 electrical contact and noticed that gases were evolved 

 in the drop. On the basis of the odors ( !) of the gases 

 they identified them as hydrogen and oxygen. They 

 then went on to obtain silver, lead and copper from 

 solutions of the compounds of these metals. In the 

 same year, and independently, the Bavarian Johann 



■" Nicholson, op. cit. (footnote 6) ; Carlisle, Cruickshanks, 

 Nicholson, et al., "Experiments in Galvanic Electricity," 

 Philosophical Magazine, 1800, vol. 7, pp. 337-347. 



248 



BULLETIN 228: CONTRIBUTIONS FROM THE MUSEUM OF HISTORY AND TECHNOLOGY 



