PSS) Se Oe 
Cig 
and always about an equal furface 
of the metal expofed: to its aétion, 
and yields in a fhort time a large 
quantity of nitrous air very conftant 
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 cagoutchouc, and, in- 
ftead of a bended glafs tube, I take 
one made of the fame elaftic gum. 
Such tube is.eafily, pode a! neal 
up pieces of caoutc 
the form of tubes, and Rickie phen 
together by their extremities. This 
fubft pofieifes aftrong 
wonderfu 
_ power of attraction for itfelf, fo 
that two pieces cut with a fharp in- 
ftrument will adhere ftrongly toge- 
ther, if joined before the cut and 
{mooth edges have been touched by 
the fingers, or before they are acad 
