This step is optional, but is essential in the cases where {HEAD ~ the above described metal chlorides} are hygroscopic in ambient air or inert to oxygen or {TAIL ~ carbon} at its melting point 
are inert to
This step is optional , but is essential in the cases where { HEAD ~ the above described metal chlorides } are hygroscopic in ambient air or inert to oxygen or { TAIL ~ carbon } at its melting point
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH OTH REL REL OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH