electrolyte surface to rise and fall as a result of the acceleration or travel of a vehicle according to the invention the demisting flame arrestor 12 has both hydrophilic and hydrophobic properties so that the collection of water vapor may be promoted by the hydrophilic property and the repulsion of water droplets may be promoted by the hydrophobic property generally speaking hydrophilic and hydrophobic properties are mutually exclusive properties within any homogeneous material it is therefore an object of the invention to construct the flame arresting demister as a composite material or as an assembly of hydrophilic and hydrophobic materials in such a way that hydrophilic and hydrophobic zones are distributed throughout the composition in one embodiment a demisting flame arrestor 12 comprises a composite material that is between about 10 and about 90 hydrophilic with the balance of the composite being hydrophobic the hydrophilic material may be a metal that is readily wettable by the electrolyte but not corrodible metals such as nickel stainless steel noble metals and plated metals u2014 such as iron or steel plated with nickel or chromium u2014 are examples of hydrophilic materials that are suitable for use in the demisting flame arrestor the hydrophobic material may be a thermoplastic polymer such as teflon or polypropylene or some other material that is stable in the electrolyte and that possesses the desired water repulsion properties in one embodiment as shown in the figure demisting flame arrestor 12 comprises a composite having.