The method 1 including collecting gas molecules containing the other of {HEAD ~ said isotopes} traveling along said {TAIL ~ other path} 
traveling along
The method 1 including collecting gas molecules containing the other of { HEAD ~ said isotopes } traveling along said { TAIL ~ other path }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL OTH TAIL TAIL TAIL TAIL TAIL TAIL