Uses liquid propylene instead of liquid inert hydrocarbon diluent. Reconstitution in sterile diluent produces a solution for subcutaneous injection. Excess ethylene and olefin diluent are flashed off. The polymer does not dissolve into a diluent, but rather rides on the liquid propylene. In solvent extraction the diluent has potentially several uses. If the diluent is unknown, equilibrium supernatant is readily obtained by centrifugation. Water is the main diluent for water-borne paints, even the co-solvent types. The diver can manually control the mixture by adding diluent gas or oxygen. This is done by combining a liquid diluent with the freeze-dried powder, mixing, then injecting. Typical diluent in this case is naphtha or condensate. Air is used as a diluent to decrease oxygen concentration. Sodium sulfate is used as a diluent for food colours. The technique involves simultaneously venting the loop and injecting diluent. If the bacterial suspension is too turbid, it can be diluted with more diluent. Lidocaine is often added to cocaine as a diluent.