A process for recovery oil includes recovering an oilwater mixture from an oil well. The engine has an exhaust gas recirculation system utilizing pressure sensors upstream and downstream of an orifice. The apron carries moving rakes which lift and turn the material. A scribe guide extends from said alignment head, said scribed guide including a scribing side. The one or more symbols then may be transmitted to a receiver using transmission techniques well known to those skilled in the art. In one aspect, the concentrations of both elemental and oxidized mercury are preserved by the apparatus for analysis.