From Washington Coalfields: The geographical distribution of the principal coal areas of Washington is shown in figure 1. Detailed information concerning these fields is given in Bureau of Mines Technical Paper 491. Further information on the minor coal areas is given in two bulletins of the Washington Division of Mines and Geology. Analyses, plastic properties, free-swelling indexes, and agglutinating values of the separate coals, together with data on yields of carbonization products and properties of the cokes produced in laboratory tests and under operating conditions."