I would use vinegar instead of adding in a bit of lemon like your doing , you really should never shoot lemon juice it's very bad for you. Are you using # 4 powdered heroin , because if you are there's no need to heat it. The only thing i would heat and only if it didn't dissolve on it's own would be the crack. But I found that it always went into solution nicely when I was using distilled vinegar. If it didn't I would slowly heat it up and mix it , you should always put the crack into the solution first IMO.