30 July 2018 | ZeroGeoengineering.com |Among the objects of this invention is the provision of a process whereby smoke producing liquids may be dropped from aircraft, wherein the liquid reacts with one or more of the constituents of the air or atmosphere and generates a smoke screen as it falls.

UNITED STATES  PATENT  1,619,183         Patented  1 March 1927

Link To Patent US1619183