^^^^^s^^ss^^s^^^^^ 



Figure 6. — Joseph Priestley's trough battery. {USNM 5/5/7^; 

 Smithsonian photo 47048- A.) 



one had 100 pairs of plates 6 inches square, and one 

 had 150 pairs of plates 4 inches square. Alum and 

 "nitrous acid" were used to charge the cells. 



A trough battery could not be cleaned without 

 some difficulty; and as long as the charge was in the 

 battery it tended to dissolve any corrodible electrode. 

 C. H. Wilkinson's "plunge" battery 1- avoided this 

 dissolution by suspending the electrodes from a rod 

 so that all the electrodes could be immersed at the 

 same time and could be removed from the cor- 

 rosive acid when not in use. In addition, both sides 

 of an electrode were used, increasing the current 

 output for a given amount of metal. A similar form 

 of such a plunge battery was constructed by Pepys 

 (fig. 10). J. G. Children made a plunge battery of 

 20 pairs of copper and zinc plates, each 4 feet high 

 and 2 feet wide, with a "charging" fluid of dilute 

 nitrous and sulfuric acid.i' In the following year, 

 the "Great Battery" '* of the Royal Institution of 

 Great Britain was constructed on a similar plan (fig. 

 11). In this battery there were 200 porcelain troughs, 

 each of which constituted a plunge battery of 10 pairs 

 of electrodes that were 4 inches square. With the use 



'2 C. H. Wilkinson, "On the Means of Simplifying and Im- 

 proving the Galvanic Apparatus," Nicholson's Journal, 1804, 

 vol. 8, pp. 1-5; "Facts upon which Deductions Are Made to 

 Show the Law of Galvanism in Burning the Metals, According 

 to the Disposition of Equal Surfaces of Charged Metallic 

 Plates," Nicholson's Journal, 1804, vol. 7, pp. 206-209; "De- 

 scription of an Improved Galvanic Trough," Philosophical 

 Magazine, 1807, vol. 29, pp. 243-244. 



■3 John G. Children, "An Account of Some Experiments, 

 Performed with a View to Ascertain the Most Advantageous 

 Method of Constructing a Voltaic Apparatus, for the Purpose 

 of Chemical Research," Philosophical Transactions, 1809, vol. 99, 

 pp. 32-38. 



'* Humphrey Davy, "On Some New Electrochemical Re- 

 searches, on Various Objects, Particularly the Metallic Bodies, 

 from the Alkalies and Earths, and on Some Combinations of 

 Hydrogene," Philosophical Transactions, 1810, vol. 100, pp. 16-74. 



r^.z. 



tl^zJvz^ii^ ^^yia^^TzAiy). 



fy.3. 



ii. #c-r 



Fy-4- 



4£c^i^i^e^ it£<iy^ M^ ^^ua.: 3. 



^yza. J. 



Figure 7. — Nicholson's trough battery. From 

 Nicholson, ed., A Journal oj Natural Philosophy, 

 Chemistry, andthe Arts, 1804, vol. 8, p. 64, pi. 3. 



of this battery Davy isolated the alkaline earth 

 metals.'^ 

 Volta's pile of n pairs of metals increased what he 



1'' Humphrey Davy, "Electro-Chemical Researches on the 

 Decomposition of the Earths; with Observations on the Metals 

 Obtained from the Alkaline Earths, and on the Amalgam 

 Procured from Ammonia," Philosophical Transactions, 1808, 

 vol. 98, pp. 333-370. 



238 



BULLETIN 228 : CONTRIBUTIONS FROM THE MUSEUM OF HISTORY AND TECHNOLOGY 



