{TAIL ~ The discharge vessel} encloses a discharge space having an ionizable filling which, in addition to Hg, contains a quantity of iodide of Na, Tl, Ho and {HEAD ~ Ca} 
{ TAIL ~ The discharge vessel } encloses a discharge space having an ionizable filling which , in addition to Hg , contains a quantity of iodide of Na , Tl , Ho and { HEAD ~ Ca }
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 OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD