196 GEOLOGY OF OHIO. 
taneous flow of carbureted hydrogen gas from the Huron shale has been 
extensively utilized. Fredonia was for many years exclusively, and still 
is partially, lighted by natural gas, and at Erie wells sunk for the pur- 
pose are supplying combustible gas which is being successfully applied 
to the heating and lighting of residences and manufacturing establish- 
ments. 
The gypsum and hydraulic lime of the Waterlime and Salina groups 
should, perhaps, be enumerated among the mineral resources of Hrie 
county, as, though not found upon the surface, they lie not far below. 
The quantity and accessibility of these materials are, however, yet so 
much in doubt that no one would be justified in anticipating a great 
increase in the wealth of the county from this source. 
In concluding this report, it affords me pleasure to acknowledge my 
obligations to Dr. A. H. Agard, Mr. L. P. Wheelock, and Hon. D. C. 
Richmond, for valuable assistance rendered in my explorations of the 
county. 
