270 



BENJ. PTKE'8, JR.. DESCRIPTIVE CATALOGUE. 



Electrical Battery, with fifteen Jars. (Fig. 292.) This 

 represents an electrical battery of fifteen jars in the act of 

 being charged from the conductor of an electrical machine, 

 with Cuthbertson's balance electrometer, and an arrange- 

 ment for striking metallic oxides attached. 



Price, fifteen quart jars, $22.50. 

 " half gallon " $30.00. 

 " gallon " $40.00. 



Leyden Jar with Movable Coatings. (Fig. 293, next page.) 

 This consists of a glass jar, with a double set of movable 

 coatings, either of which may be adapted to it at pleasure, 

 the outer coating being a tin case large enough to admit 

 the jar easily within it, and the inner coating a similar case 

 sufficiently small to pass readily in the inside of the jar. 

 The charging wire of the inner ( iting should be surrounded 



