1902

Charles A. DOREMUS, of New York: "Process of manufacturing hydrofluoric acid", US Patent 754,978; filed July 31, 1902; pat. March 22, 1904

1915

Ralph S. SHERWIN, assignor to Aluminum Company of America, Pittsburgh: "Apparatus for condensing and utilizing hydrofluoric acid", US Patent 1,294,546; filed Jan. 13, 1915; pat. Feb. 18, 1919

1917

Howard Field CHAPPELL, of New York: "Manufacture of hydrofluoric acid from silicon fluorid", US Patent 1,244,032; filed April 17, 1917; pat. Oct. 23, 1917

Robert M. CATLIN, assignor to Catlin Shale Products Company, of Wilmington Del.: "Process of making hydrogen fluorid", US Patent 1,293,703; filed June 9, 1917; pat. Feb. 11, 1919

1925

William J. HARSHAW, of Shaker Heights Village, and Charles D. PARKE, of Cleveland, Ohio, assignors to the Harshaw, Fuller and Goodwin Company, of Cleveland, Ohio: "Method of making hydrofluoric acid", US Patent 1,665,588; filed Feb. 19, 1925; pat. April 10, 1928

1928

William J. HARSHAW, of Shaker Heights Village, and Charles D. PARKE, of Cleveland, Ohio, assignors to the Harshaw Chemical Company, of Cleveland, Ohio: "Apparatus for making hydrofluoric acid", US Patent 1,842,092; filed Feb. 19, 1925, divided and this application filed Feb. 4, 1928; pat. Jan. 19, 1932

1932

Philipp OSSWALD, Otto SCHERER, assignors to I. G. Farbenindustrie Aktiengesellschaft, Frankfort-on-the-main, Germany: "Process for preparing pure hydrogen fluoride", US Patent 1,960,347; filed Aug. 24, 1932, patented May 29, 1934

1935

James C. LAWRENCE, assignor to E. I. Du Pont de Nemours & Company, of Wilmington, Del.: "Improvement in or relating to the manufacture of hydrofluoric acid", British Patent GB 462,131; filed: Sept. 2, 1935; compl. specif. left: Sept. 2, 1936; pat. March 2, 1937

1942

Louis S. KASSEL, assignor to Universal Oil Products Company, Chicago, Ill.: "Recovery of hydrogen fluoride", US Patent 2,392,048; filed Nov. 16, 1942, patented Jan. 1, 1946

Walter A. SCHULZE, William N. AXE, assignors to Phillips Petroleum Company: "Hydrogen fluoride recovery process", US Patent 2,379,041, filed Dec. 5, 1942, patented June 26, 1945

1943

Robert E. BURK, assignor to Standard Oil Company, Cleveland, Ohio: "Recovery of Catalysts", US Patent 2,400,874, filed Jan. 6 1943, patented May 28, 1946

Maryan P. MATUSZAK, assignor to Phillips Petroleum Company: "Recovery of hydrofluoric acid", US Patent 2,371,341, filed Aug. 6, 1943, patented March 13, 1945

1946

William F. GRESHAM, assignor to E. I. Du Pont de Nemours & Company, Wilmington, Del.: "Recovery of hydrogen fluoride - boron trifluoride catalysts", US Patent 2,462,739, filed Nov. 13, 1946, patented Feb. 22, 1949

1950

Joe E. PENICK, assignor to Socony-Vacuum Oil Company Inc.: "Hydrogen fluoride recovery", US Patent 2,591,096, filed May 8, 1950, patented April 1, 1952

1955

Jesse Craig YACOE, assignor to E. I. Du Pont de Nemours and Company, Wilmington, Del.: "Slurry process for the manufacture of hydrogen fluoride", US Patent 2,846,290; filed Nov. 28, 1955; pat. Aug. 5, 1958

1967

Roy J. LARAN, Albert P. GIRAITIS, Paul KOBETZ, assignors to Ethyl Corporation, N.Y.: "Process for the production of anhydrous hydrogen fliuoride", US Patent 3,501,268; filed May 18, 1967; patented Mar. 17, 1970

1974

Carl Raymond FAUST, assignor to E. I. Du Pont de Nemours & Company: "Process for making anhydrous hydrogen fluoride from fluosilicic acid", US Patent 3,914,398; filed Dec. 16, 1974; patented Oct. 21, 1975

1999

Louis J. LAMB: "Apparatus and method for producing HF from phosphate rock", US Patent 6,179,901; filed June 14, 1999; patented Jan 30, 2001

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