697189-A is referenced by 212 patents.
697,189. Gasifying unmined coal. NATIONAL RESEARCH DEVELOPMENT CORPORATION. March 24, 1952 [April 9, 1951], No. 8241/51. Class 55(ii) A gasification channel 4 in a dipping coal seam 1 extends horizontally between a gaseous medium intake shaft 5 and a gas offtake shaft 6 and a pipe line 7 in shaft 5 includes a pump 7a either for introducing water if the seam is dry or for withdrawing surplus water if wet, the level 10 of water in the channel being so adjusted as to keep the gasifying medium in close contact with the ignited coal without effecting such evaporation as would quench the gasification. The air &c. is prevented thereby from percolating through the accumulating ash and debris 9a to the offtake. The water level is measured by means of a pipe 8 as by determining the pressure required to cause air to bubble through the water.; Specification 674,082 is referred to in the Provisional Specification.