Yes, MattD already got to 1cc=1ml.
Most powders can be "assumed" to be close to 1gm/mL, or 1gm = 1mL (cc) in volume. Therefore, if you have 99ml of oil and 1 gram of powder, you will get a total soln of 100ml. That is just an estimation and is in no way accurate, but it is "close enough" for our purposes. Unless we're working with lead here, no big deal