[ *72 ] 



in any way. To the extremity of 

 iucti a tube I adapt a hollow glafs 

 {topper of a conical form, fo as to 

 fit almofr. all bottles. A brafs ring 

 forced over the neck of the gum 

 bottle prefTes its fubftance againft 

 the glafs {topper, and prevents the 

 nitrous air ruining out. 



It is to be obferved, that nitrous 

 acid will at laft deftroy the elaftic 

 gum bottles by making its infide 

 brittle, efpecially if the acid is very 

 concentrated. 



Though good nitrous air may 

 be obtained by many ways, yet this 

 air lofes gradually its ftrength, and 

 in a few days, if in contact with 

 water, becomes very much weak- 

 ened ; fo that it muft be either made 

 new almofb every day, or we cannot 

 be fure of the remit of the expe- 

 riment.. 



The 



