1867.] for multiplying and maintaining Electric Charges. 69 



tricitj carried By eacli drop, as it breaks from the continuous water 

 above, and Y the potential of the inner coating of the lower jar, the 

 potential of the uninsulated water being taken as zero. The practical 



Eig. 2. 



limit to the charges acquired is either when one or other of them is so 

 strong as to cause sparks to pass across some of the separating air-spaces, 

 or to throw the drops of water out of their proper course and cause 

 them to fall outside the receiver through which they ought to pass. 

 It is curious, after commencing with no electricity except a feeble 

 charge in one of the jars, only discoverable by a delicate electrometer, 

 to see in the course of a few minutes a somewhat rapid succession of 

 sparks pass in some part of the apparatus, or to see the drops of water 

 scattered about over the lips of one or both the receivers. 



The Ley den jars represented in the sketch (fig. 2) are open-mouthed jars 

 of ordinary flint glass, which, when very dry, I generally find to insulate 

 electricity with wonderful perfection. The inside coatings consist of 

 strong liquid sulphuric acid, and heavy lead tripods with vertical stems 

 projecting upwards above the level of the acid, which, by arms projecting 

 horizontally above the lip of the jar, bear the inductors and receivers as 

 shown in fig. 2. Lids of gutta percha or sheet metal close the mouth 

 of each jar, except a small air-space of from J to 5 of an inch round the 

 projecting stems. If a tube (fig. 3) be added to the lid to prevent 

 currents of air from circulating into the interior of the jar, the in- 

 sulation may be so good that the loss may be no more than one pey 

 cent, of the whole charge in three or four days. Two such jars may 



