01442cam a22003011 4500 gs 35000001 DLC 20260227111339.0 790607s1934 ilua s000 0 eng gs 35000001 (OCoLC)5045725 DLC TxCM DLC premarc TP325 .I63 1934 Illinois State Geological Survey Contributions to the study of coal: A proposed simplification of the Parr unit coal formula, by Gilbert Thiessen. Ash-to-mineral matter correction in coal analyses, by Gilbert Thiessen. Unit coal as a basis of coal standardization as applied to Illinois coals, by G. H. Cady and O. W. Rees. Studies of the graphical method of calculating pure coal calorific value, by Gilbert Thiessen and Frank H. Reed. Urbana, Illinois, Printed by authority of the state of Illinois, 1934. 99 p. illus. Its Report of investigations no. 32 At head of title: State of Illinois. Department of Registration and Education. Division of the State Geological Survey. Coal Analysis. Coal Illinois. Thiessen, Gilbert, 1905- Cady, Gilbert H. (Gilbert Haven), 1882- Rees, Orin Wainwright, 1898- Reed, Frank Hynes, 1890- Illinois State Geological Survey. Report of investigations no. 32. 27157 27157