VOLTAIC BATTERIES. 51 



more so, than the galvanic battery itself. The various forms 

 of this instrument will be described at the end of this chapter. 

 In cases where the continuous current is required, the battery 

 alone can be used. 



VOLTAIC BATTERIES. 



It will be seen from what has been said, that, for the due 

 application of Galvanism as a remedial agent, it is essential to 

 have a full understanding of the construction of Batteries and 

 their manipulation. 



The first of these instruments which we shall describe is that 

 represented in Fig. 7, known as Cruickshank's Battery. It consists 



fig. 7. 



of a series of pairs of zinc and copper plates fixed into a trough 

 of wood, and may be excited either by dilute sulphuric acid, or 

 by a solution of sulphate of copper, which latter, as Dr. Fyfe* 

 has shown, increases the electro-chemical intensity of the elec- 

 tric current. This form of apparatus is neither so convenient 

 as, nor does it possess the power of, the modern arrangements 

 which we shall presently describe ; but as many such instru- 

 ments are still in use, we have deemed it necessary to make 

 mention of it. The battery of Dr. Babington is formed on the 

 same principle as the preceding, with the exception that the 

 plates of copper and zinc, usually about four inches square, are 

 united together in pairs, by soldering at one point only, and 

 are excited by immersion into a trough of earthenware, divided 

 into ten or twelve equal portions, and filled with dilute sul- 

 phuric acid. In both these batteries the liquid should consist 

 of about one part acid to fifteen or sixteen water. The plates 

 are attached to a strip of wood, and so arranged that each pair 



* London and Edinburgh Philosophical Magazine, vol. xi. page 145. 

 c2 



