An amount of granulated activated charcoal (Norit) equal to half the weight of the oil is added to the solution. The solution is filtered through fine filter paper and the alcohol is removed by evaporation. The residue is a translucent amber oil With the appearance and consistency of dark honey. The term “reefer” has sometimes been used to describe a marijuana cigarette which has been impregnated with cannabis extract. This may be accomplished by working the cannabis oil in with the marijuana or tobacco to be rolled, painting the paper with oil before rolling, dipping the rolled joint in tincture of cannabis and letting it dry, or injecting the rolled joint with cannabis tincture and letting it dry. The high potency and small volume of cannabis oil, in conjunction with anti-marijuana laws in many states, has added up to high potential profits for smugglers of the oil and new problems for law enforcement agencies. In the United States, the Drug Enforcement Administration (Drug Enforcement, 1973) has commented on the new problem (see Michael Starks’ Marijuana Potency for an excerpt) and describes various devices they have seized.