Chap. 4.] Elettricai Battery. 33$ 



The top and uncoated part of the jar mould be 

 kept dry and free from dud ; and after the explofion 

 has taken place, a wire from the hook is to be con- 

 nected to the ball, and left there till the battery is to 

 be charged again, by which means the inconveniences 

 arifing from the frequent refiduum of a charge will be 

 obviated. 



Every broken jar in a battery muft be taken away, 

 before it is poffible to charge the reft. 



It has been recommended, not to difcharge a bat- 

 tery through a good conductor, if the circuit is not at 

 lead five feet long ; but it mutt be obferved, that in 

 proportion to the lengthening of the circuit the force 

 of the mock will be leffened. 



Jars made of the green glafs, manufactured at New- 

 caftle, are laid to endure an explofion without a pro- 

 bability of breaking. 



If the fpark from the explofion is concentrated, by 

 caufing it to pafs through fmall circuits of non-con- 

 ducting fubftances, the force of the battery will be 

 confiderably increafed. For this purpofe, caufe the 

 fpark to pafs through a hole in a plate of glafs one- 

 twelfth or one-fixth of an inch diameter, by which 

 means it will be more compact and powerful. By 

 wetting the part round the hole, the fpark, by con- 

 verting this into vapour, may be conveyed to a greater 

 diftance, with an increafe of rapidity, attended with a' 

 louder noife than common. Mr. Morgan, by at- 

 tending to thefe and fome other circumltances, has 

 melted wires, &c. by the means of fmall bottles. 



If the charge of a ftrong battery is pafled through 

 two- or three inches of fmall wire, the latter will fome- 

 times appear red hor, firft at the politive fide j and 

 the rednefs will proceed towards the other end. 



If a battery i* difcharged through a frnall fteel nee- 

 dle, 



