262 REVIEWS 



phology, suborders on the form of aperture and operculum, and families 

 on the presence of cardelles, lyrula, ovicells, and radicells. 



With the increased recognition of the value of bryozoans as horizon- 

 markers, the student will find this systematic report a reference of 

 constant value. 



A. C. McF. 



Louisiana Lignite. By Robert Glenk. Department of Conserva- 

 tion, Division of Economic Geology, State of Louisiana, 

 Bull. No. 8. New Orleans, 192 1. 



Although Louisiana lignite has been consistently mapped on all 

 fuel maps of late years as a possible source of low-grade fuels, it has not 

 until recently begun to receive the attention that it merits. The 

 report here reviewed shows a gratifying interest by the state of Louisiana 

 in its available resources — an interest that, since the days of Harris' 

 and Veatch's work on the state survey, appeared to have flagged. 



The lignite of Louisiana is of Eocene age and distributed vertically 

 in the Wilcox, Claiborne, and Jackson groups. It varies in thickness 

 from a few inches to twenty feet. Interesting paleobotanical collections 

 have been made from it. In the adjacent states of Texas and Arkansas 

 lignite is mined in considerable quantities by stripping the overburden, 

 or by the room-and-pillar method where the dip of the lignite bed is 

 appreciable; similar methods, though not yet used in Louisiana, might 

 well be applied there in the future. 



Figures expressing the lignite reserves of the state are not presented; 

 they would be interesting and use'ul. Analyses of several Louisiana 

 lignites yielded the following: 



Percentage 



Moisture 5-47 



Volatile combustible matter 30-75 



Fixed carbon 5-40 



The highest thermal value obtained was 8,046 B.T.U.'s. The analyses 

 presented show Louisiana lignite to be of an intermediate grade. With 

 destructive distillation the end products were: 



Percentage 



Aqua ammonia 20 -30 



Tar 4 5-5 



Carbonized residue. 50 -56 



Gas and loss 18 -20 



The carbonized residue has a heating value equal to good anthracite; 

 an average ton of lignite yields 8,000 cubic feet of gas (mainly hydrogen, 



