A vent is formed in the flask in such manner as to prevent accidental spillage of liquid therefrom while also permitting entrance of air into {HEAD ~ the flask} when {TAIL ~ negative internal pressure} is applied during removal of liquid therefrom 
A vent is formed in the flask in such manner as to prevent accidental spillage of liquid therefrom while also permitting entrance of air into { HEAD ~ the flask } when { TAIL ~ negative internal pressure } is applied during removal of liquid therefrom
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH