[ "6 ] 



following letter by his ingenious friend. Should any perfon wifh 

 to try the experiment therein mentioned, relative to the abforption 

 of air by mercury, it will make it ftill more decifive and 

 fatisfadlory. If after the ciftern is finally clofed, it, and about 

 half an inch of the tube immediately adjoining it, be dipped 

 in melted wax and fufFered to cool, and this repeated three or 

 four times. 



