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