What was found
AFTER APPROX 50 MINUTES OF FLIGHT, F/A NOTICED A VERY SLIGHT ODOR. ABOUT 5-8 MINUTES LATER, SHE BEGAN TO NOTICE A VERY SLIGHT HAZE WHICH BEGAN TO THICKEN RAPIDLY. WE BEGAN AN EMERGENCY DESCENT AND AS SOON AS THE THROTTLES WERE RETARDED THE SMOKE BEGAN TO DISSIPATE. CLEARING IN ABOUT 3 MINUTES. HOWEVER THE ODOR REMAINED. ALL BLEED INDICATIONS WERE NORMAL. CABIN DUCT TEMP WAS 80 DEGREES AND HAD NOT BEEN MOVED SINCE LEVEL OFF (COCKPIT READ 60 DEGREES)