CHAP. I.] ELECTRICITY AND MAGNETISM. 



59 



for a larger charge can be put into it ; its capacity is 

 greater. A Leyden jar made of thin glass has a 

 greater capacity as an accumulator than a thick one of 

 the same size ; but if it is too thin it will be destroyed 

 when powerfully charged by a spark actually piercing 

 the glass. " Toughened " glass is less easily pierced 

 than ordinary glass, and hence Leyden jars made 



Fig. 33- 



of it may be made thinner, and so will hold a greater 

 charge. 



If, however, it is desired to accumulate a very great 

 charge of electricity, a number of jars must be em- 

 ployed, all their inner coatings being connected together, 

 and all their outer coatings being united. This arrange- 

 ment is called a Battery of Leyden jars, or Leyden 



