Fire Controlled by Flat Sprays During the past three years, the Indianapolis, Ind., Fire Department has been experimenting with a new type of flat spray with hydraulic diffusion. The results of the tests showed that these sprays were successful in many types of fire control, including magnesium alloys, all types of volatiles, and grass fires of very large area. Contrary to past beliefs concerning the use of water on magnesium alloy fires, this flat spray has proven its worth in controlling the fire and preventing explosions. When used on such a fire, the spray tends to exclude most of the oxygen, thus causing a crust to form over the burning magnesium. This further prevents the inclusion of oxygen. Finally, the fire becomes just a smouldering mass, with little dissipation of heat. Because of the finely diffused nature of the stream, it extinguishes by suffocation.