Ok first of all everyone take note of the following.
In chemistry, separating 2 compounds that are in a heterogeneous form, meaning a single powder/solution that has more than one separate chemical in it, you have to play magic tricks and use the differences between the 2 to separate them.
In the most BASIC case, freebase cocaine can be disolved in ether or another non-polar solvent, leaving behind anything polar or water soluble to be then washed away by adding water, separating the 2 liquids, and throwing the water out.
In another BASIC case, cocaine HCl can be disolved in something like water, and "washed" with a non polar solvent, to remove anything soluble in said non polar solvent, but not the cocaine, which stays in the water.
Those are your 2 basic washes of cocaine. They can be done easily.
Now, if your going to be just doing that, thats fine, you should realize that many drugs including amphetamine, methamphetamine, procaine, and a lot of the other active drugs used to cut cocaine, also share chemical properties with cocaine for our purposes here. That means whatever you do as far as washing, the active crap stays with the cocaine. As well if you convert from a hcl to a base or from a base to a hcl, most of those active cuts will follow the same path as cocaine, going from base to hcl, or from hcl to base, just like the cocaine will.
You have to find a property of one of the drugs you have (assuming you KNOW what you have), that is either different or can be used to your advantage.
Some of these properties are increased or decreased solubility at certain temperatures, another would be using specific solvents that are known to disolve one drug but not another when both are in either base or hcl form
The main chem mentioned in this thread is acetone, which is a good chem for this purpose, however it doesnt clean everything, you have to know what you have first to know if it will clean it out.
For now, you have little way of knowing what else is in the coke, you can ASSUME but that isnt for sure.
Talc is not soluble in water, probably soluble in acetone.
Procaine HCl is soluble in water, and probably not acetone, the base is not soluble in water but should be soluble in acetone
Mannitol is a sugar and is soluble in water, but most sugars are insoluble in acetone.
Some of this stuff is incredibly hard to find, even in an MSDS, i have solomons org chem next to me and i still cant find out much about some of these chems solubility in things other than water. So in most cases i can guess based on the molecule but there are odditys of nature that make no sense, even worse with acetone which disolves things non-polars dont. You either have to know or try it and see what comes out.