VOL. XLIX.] PHILOSOPHICAL TRANSACTIONS. 631 



contained in the substance of the prime conductor ; but which is now repelled 

 and driven away, by the atmosphere of the glass tube, from the parts of the 

 prime conductor, opposite and nearest to that atmosphere, and forced out upon 

 the surface of the prime conductor at its other end, and on the threads hanging 

 to it. Were it any part of the atmosphere of the glass tube, that flowed over 

 and along the prime conductor to the threads, and gave them atmospheres (as in 

 the case when a spark is given to the prime conductor, from the glass tube), 

 such part of the tube's atmosphere would have remained, and the threads con- 

 tinue to diverge; but they close on withdrawing the tube, because the tube takes 

 with it all its own atmosphere, and the electric matter, which had been driven 

 out of the substance of the prime conductor, and formed atmospheres round the 

 threads, is thereby permitted to return to its place. 



Take a spark from the prime conductor, near the threads, when they are di- 

 verged as before, and they will close. — J'or by so doing you take away their at- 

 mospheres, composed of the electric matter driven out of the substance of the 

 prime conductor, as aforesaid, by the rejiellency of the atmosphere of the glass 

 tube. By taking this spark, you rob the prime conductor of part of its natural 

 quantity of the electric matter ; which part so taken is not supplied by the glass 

 tube; for when that is afterwards withdrawn, it takes with it its whole atmo- 

 sphere, and leaves the prime conductor electrized negatively, as appears by the 

 next operation. 



Then withdraw the tube, and they will open again. — For now the electric 

 matter in the prime conductor, returning to its equilibrium, or equal diffusion, 

 in all parts of its substance, and the prime conductor having lost some of its na- 

 tural quantity, the threads connected with it lose part of theirs, and so are elec- 

 trized negatively, and therefore repel each other, by Pr. 3. 



Approach the prime conductor with the tube near the same place as at first, 

 and they will close again. — Because the part of their natural quantity of electric 

 fluid, which they had lost, is now restored to them again, by the repulsion of 

 the glass tube forcing that fluid to them from other parts of the prime conduc- 

 tor : so they are now again in their natural state. 



Withdraw it, and they will open again. — For what had been restored to them 

 is now taken from them again, flowing back into the prime conductor, and 

 leaving them once more electrized negatively. 



Bring the excited tube under the threads, and they will diverge more. — Be- 

 cause more of their natural quantity is driven from them into the prime conduc- 

 tor, and so their negative electricity increased. 



Exper. 3. — The prime conductor not being electrified, bring the excited tube 

 under the tassel, and the threads will diverge. — Part of their natural quantity is 



