In individual cases, {HEAD ~ the strength} can be increased by admixing {TAIL ~ graphite} with the powder, although even this should be avoided as far as possible 
increased by admixing
In individual cases , { HEAD ~ the strength } can be increased by admixing { TAIL ~ graphite } with the powder , although even this should be avoided as far as possible
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL REL REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH