{HEAD ~ Gas} can be introduced into {TAIL ~ the liquid} in any one or all of the chambers 
introduced into
{ HEAD ~ Gas } can be introduced into { TAIL ~ the liquid } in any one or all of the chambers
HEAD HEAD HEAD HEAD HEAD OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH