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There are a few types of heroin I guess, if you wanna call black tar "heroin." The brown granular stuff is h base AFAIK better for smoking... i've heard of people booting it, i guess some people add a little bit of lemon juice to the water they cook it in to make it a bit more soluble, the "china white" is h hcl for booting and sniffing. IDK all of the above are something you don't wanna get involved with. Black tar is like less than 10% h and FWIU it is more like a half finished batch of H. Someone more chemistry minded might be able to get more technical.
Don't hate the black, don't hate the white,
If you get bitten, just hate the bite