The selective transmission may be achieved by providing {HEAD ~ a wall section} consisting of {TAIL ~ a selectively permeable material}, chosen to permit the transfer of only the gaseous substance to be monitored between the interior and the exterior of the chamber 
consisting of
The selective transmission may be achieved by providing { HEAD ~ a wall section } consisting of { TAIL ~ a selectively permeable material } , chosen to permit the transfer of only the gaseous substance to be monitored between the interior and the exterior of the chamber
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH