{HEAD ~ Addition} of up to 60 wt% organic acid to {TAIL ~ the calcium hydroxide solution} or suspension is preferred 
to
{ HEAD ~ Addition } of up to 60 wt% organic acid to { TAIL ~ the calcium hydroxide solution } or suspension is preferred
HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH