500 Mr. J. E. Bowman on the Electricity of Gun-Cotton. 

 or 



(l-x3)^-(3p + 6)a;*^-3(p+l)(p + >2)xu = O i 

 an equation of the second order only. 



If +*3) g + p (/>-!) (p-^^O, 



£ , = D / '~ 3 tt will transform it to 



(1+ ^ ) S- ( ^- 6) ^ + 3 ^~ 1)( ^" 2) ^ ==D ~ ;,+20=X - 

 And if (1 +*?) j2 - P (p + l) (p + 2) y = 0, 



i/=T>-p~ 5 u will transform it to 



Gunthwaite Hall, October 20, 1846, 

 Near Barnsley, Yorkshire. 



LXX. On the Electricity of Gun-Cotton. By Mr. J. E. 

 Bowman, Demonstrator of Chemistry, King's College. 



To Richard Phillips, Esq. 

 Dear Sir, 



SINCE every one appears to be more or less engaged in the 

 manufacture of the so-called "gun-cotton," it may be in- 

 teresting to some of your readers to know that it is capable of 

 being applied to a purpose different from any hitherto de- 

 scribed, viz. that of insulating an electrically charged body. 

 I was yesterday engaged in unravelling some cotton which 

 had matted together while in the acid, when I was struck with 

 the tenacity with which it adhered to my fingers; and on 

 lightly holding a small flock of it, and approaching a finger of 

 the other hand, or any foreign body, found that it was strongly 

 attracted towards it, thus differing essentially from the unpre- 

 pared cotton. I then subjected a little sewing cotton to the 

 action of the acid, with the view of obtaining it in a more con- 

 venient form for testing its insulating power, and suspended 

 from a brass rod two equally charged copper balls, one with 

 white silk and the other with the prepared cotton. By ex- 

 amining the two balls at short intervals of time by means of 

 a delicate gold-leaf electrometer, I found that the one sus- 

 pended by the cotton retained its charge considerably longer 



