( i7i ) 



and always about an equal furface 

 of the metal expofed to its action, 

 and yields in a fhort time a large 

 quantity of nitrous air very conitant 

 in quality. Brafs feems to me to 

 give nitrous air of a much more 

 inconftant quality. Inftead of a 

 glafs bottle, I often ufe an elaftic 

 gum bottle, or caoutchouc ', and, in- 

 ftead of a bended glafs tube, I take 

 one made of the fame elaftic gum. 

 Such tube is eafily made by coiling 

 up pieces of caoutchouc bottles in 

 the form of tubes, and flicking them 

 together by their extremities . This 

 wonderful fubftance pofTefTes a flrong 

 power of attraction for itfelf, fo 

 that two pieces cut with a fharp in- 

 flrument will adhere ftrongly toge- 

 ther, if joined before the cut and 

 fmooth edges have been touched by 

 the fingers, or before they are foiled 



in 



