The second solution is then added in {HEAD ~ increments} to {TAIL ~ the first solution} while stirring to precipitate a mixture of oxygen containing compounds of said first element, said second element, cerium, and terbium 
to
The second solution is then added in { HEAD ~ increments } to { TAIL ~ the first solution } while stirring to precipitate a mixture of oxygen containing compounds of said first element , said second element , cerium , and terbium
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL 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