Anyone know what this Black Hose is.....

[TELREA]

sorry not sure if this is a problem,but not very technical minded,whilst having a go at changing the passenger side headlamp bulb this afternoon,and after several unsuccessful attempts at putting the blasted cover back on i droped it and when i tried to retrieve it under the car,i noticed the black hose in the left of the picture,i knocked against it and noticed the end of it doesn't seem to be attached to anything Sorry but if anyone can fill me in as to what this might be,most appreciated thanks

TEL.

[steve-t]

Looks like the battery gas vent.
Take a look at the battery it should have the other end attatched, its so when the battery is charging the gasses produced do not build up under the bonnet.
The gasses are explosive and corrosive
Steve