14fi Remarks on the Galvanic Battery. 



When the specific gravity of the s. z. approaches 40° B. 

 one-half of the liquid should be removed, and fresh water 

 added. It is always best, however, to keep the specific 

 gravity of the s. z. between the limits 15° to 38° B. 



If Hill's form of battery is employed, a jar of the same 

 size may be used. With plates of 50 square inches each, 

 placed at a distance of 5 inches from each other, q. is the 

 same as for Daniell's element of the ordinary size. The 

 negative plate may be made of sheet lead, having a pro- 

 tected copper wire firmly attached to it. The zinc should 

 be cast with an opening in the centre of one and one- 

 half inches in diameter. Iron bars for supporting it near 

 the top of the jar, can be cast in the zinc. This 

 battery should be started with a solution of s. z. having 

 a specific gravity of 15° B. The s. c. is dropped in through 

 the orifice in the zinc plate. The battery should be ex- 

 amined occasionally with the hydrometer, and the specific 

 gravity of the liquid never allowed to become greater 

 than 36° B. 



