I know of a test called the "Trail Test"
It involves sprinkling a small amount of the said cocaine on the surface of water in a clear drinking glass. Supposedly, if , and only if, it is cocaine, each particle will have a thin transparent trail following it as it sinks to the bottom.
Unfortunately, Procaine hydrochloride also produces trails as it sinks.
There is a bleach test you can do after this, to detect any of the synthetic anesthetics.
This reference is from "The Pleasures of Cocaine" written by Adam Gottlieb