Monkeys on Opium

Dr. Jammers, in a memoir sent to the Academie des Sciences, states that monkeys, unlike other animals, unless it is the human animal, readily acquire the habit of taking morphia. When monkeys live with opium smokers, as they do in eastern countries, where the habit is more prevalent than elsewhere, and become accustomed to the medicated atmosphere, they acquire a taste for the pipe. One particular monkey, it is said, would wait for his master to lay down his pipe and would then take it up and smoke what remained. If not allowed to do so for several days it would fall into a state of depression and inactivity which would disappear as soon as it was allowed to "hit the pipe."

Ghosh [author of a recent historical novel about opium] wrote about "a miasma of lethargy" that seemed to be always hanging over the factory's surroundings - one example was the opium addled monkeys who would lap the open sewers carrying the factory's waste.
Monkeys still have the run of the factory, eating opium waste and dozing all day. "They have become addicted to opium. Most of the time we have to drag dozing monkeys away from this place," a worker says.