Il8 ILLINOIS ACADEMY OF SCIENCE. 



the most soluble and ending with the least soluble, the arrangement 

 is as follows: No. i (residue .5 mg.), No. 3 (residue 4.4 mg.), 

 No. 4 (residue 4.5 mg.), No. 8 (residue 10 mg.), No. 2 (residue 

 II mg.), No. 14 (residue 13 mg.). No. 6 (residue 17.5 mg.). No. 9 

 (residue 18.5 mg.), No. 18 (residue 20 mg.), No. 16 (residue 

 22 mg.). No. II (residue 23 mg.). No. 10 (residue 33 mg.). No. 

 13 (residue 34 mg.). No. 7 (residue 39 mg.), No. 5 (residue 40 

 mg.), No. 12 (residue 60 mg.). No. 17 (residue 64 mg.). 



At a depth of 440 feet a 4-foot bed of a tough white, hard 

 rock, called limestone in the drill record,^ is encountered. In cold 

 hydrochloric acid it is almost insoluble, leaving a residue of 80 

 per cent. It is a siliceous dolomite. 



It is interesting to note that bed No. 18, very rich in small 

 brachiopods, lies immediately above Coal No. i at a depth of 453 

 feet. In the drill record this is called Dark Shale. To find a 

 limestone roof without intervening shale or clay is an unusual 

 occurrence. 



1 Report on the Progress and Condition of the Illinois State Museum of Natural 

 History for the years 1909 and 1910, p. 32. 



