The Specialty Chemicals Market Volume Index, a new tool created by the American Chemistry Council (ACC) strengthened during the 3rd quarter, rising 0.3 percent on a three-month moving average (3MMA) basis in August after a 0.1 percent gain in July and a weak first half of the year.   The steady declines since December reflected ongoing weakness in oilfield chemicals and a few other segments that, combined, weighed on overall volumes.   Of the 28 specialty chemical segments included in the index,...