This reduction state is sustained until {HEAD ~ the desired effects} are obtained and the temperature may be held to lengthen {TAIL ~ this reduction} 
This reduction state is sustained until { HEAD ~ the desired effects } are obtained and the temperature may be held to lengthen { TAIL ~ this reduction }
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL