A glycol proportioning station that provides a deicing mixture of glycol and water to tank trucks that in turn spray the deicing mixture onto aircraft. The invention includes a remote control that is positioned where the truck is loaded and which runs in parallel with the controls on the main unit of the system. The proportioning system operates with an economy of parts by employing constant flow rates of both water and glycol. The desired percentage of glycol in the effluent is obtained by initially setting the position of one or more modulating valves provided on each of separate water and glycol lines and then employing a refractometer feedback loop to modulate the flow in one or both of the input lines. A static mixer positioned along the effluent line upstream of the in-line refractometer provides a uniform glycol-water mixture. The system provides other novel features such as a "last fill" option that prevents the system from freezing when it is not being used.