on certain TJieorelical Opinions. 6 1 



graphs. I believe that it is. I have charged small Leyden 

 jars made of thin flint glass tube with electricity, taken out 

 the charging wires, sealed them up hermetically, and after 

 two and three years have opened and found no charge in 

 them. I will refer you also to Belli's curious experiments 

 upon the successive charges of a jar and the successive return 

 of portions of these charges*. I will also refer to the expe- 

 riments with the shell lac hemisphere, especially that de- 

 scribed in 1237. of my Researches; also the experiment in 

 124-6. I cannot conceive how, in these cases, the air in the 

 vicinity of the coating could gradually relinquish to it a por- 

 tion of free electricity, conveyed into it by what I call con- 

 vection, since in the first experiment quoted (1237.), when the 

 return was gradual, there was no coating; and in the second 

 (^'tG.), when there was a coating, the return action was most 

 sudden and instantaneous. 



xxix. Paragraphs 21 and 22 perhaps only require a few 

 words of explanation. In a charged Leyden jar I have con- 

 sidered the two opposite forces on the inductric and inducte- 

 ous surfaces as being directed towards each other through 

 the glass of the jar, provided the jar have no projection of 

 its inner coating, and is uninsulated on the outside (1682.). 

 When discharge by a wire or discharger, or any other of 

 the many arrangements used for that purpose is effected, 

 these supply the "some other directions" spoken of (1682. 

 1683.). 



xxx. The inquiry in paragraph 23, I should answer by 

 saying, that the process is the same as that by which the 

 polarity of the sphere B (iv., v.,) would be neutralized if the 

 spheres A and C were made to communicate by a metallic 

 wire; or that by which the 100 or 1000 intermediate spheres 

 (x.) or the myriads of polarized conducting particles (xi.) 

 would be discharged, if the inner sphere A, and the outer 

 one C, were brought into communication by an insulated 

 wire ; a circumstance which would not in the least affect the 

 condition of the power on the exterior of the globe C. 



xxxi. The obscurity in my papers, which has led to your 

 remarks in paragraph 25, arises, as it appears to me (after 

 my own imperfect expression), from the uncertain or double 

 meaning of the word discharge. You say, " if discharge 

 involves a return to the same state in vitreous particles, the 

 same must be true in those of the metallic wire. Wherefore 

 then are these dissipated when the discharge is sufficiently 

 powerful ? " A jar is said to be discharged when its charged 



* BMotheca Italiaw, 1837, Ixxxv., p. 417. 



