Thus, one may employ a partial ester of phosphoric or phosphorous acid with a mono or polyhydric alcohol such as hexylene glycol, ethylene glycol, di- or tri-ethylene glycol or higher polyethylene glycol, polypropylene glycol, glycerol, sorbitol, mono or diglycerides of fatty acids, etc. in which one, two or more of the alcoholic OH groups of the molecule may be esterified with the phosphorus acid