80 PROCEEDINGS OF THE AMERICAN ACADEMY. 



derived from tlie " thirty-foot " sand alone, which rock was found at 

 a depth of 1,510 feet. 



Date of Collec tion of Samples. Percentage of Nitrogen found. 



August 1, 1896 (1) 1.46 



(2) 1.48 



April 12, 1897 (1) 2.10 



(2) 2.11 



April 24, 1897 (1) 2.10 



(2) 2.09 



May 27, 1898 (1) 1.49 



(2) 1.48 



5. Well on the Hamilton farm, Neville Island in the Ohio River, 

 7 miles west from Pittsburgh. The gas was derived from the Third 

 Sand, which was reached at a depth of 1,580 feet, although there was a 

 slight flow of gas from the Fifth Sand, which was reached at 1,729 feet. 

 The well was drilled during the spring of 1898. The first sample of 

 gas below mentioned was taken about 24 hours after the gas had been 

 turned into the mains. 



Date of Collection of Samples. Percentage of Nitrogen found. 



May 16, 1898 (1) 1.78 



(2) 1.76 



May 19, 1898 (1) 1.74 



(2) 1.74 



6. Well on the King farm at IMurraysville, 18 miles east from Pitts- 

 burgh. The gas is derived from the 3Iurraysville Sand at a depth of 

 1,336 feet. The well was drilled in 1887. Analyses of samples taken 

 on a single date are presented, but this gas is of interest in the present 

 connection, as the Murraysville gas field was among the earliest explored. 

 The pressure in the rock has fallen from about 500 pounds to so low a 

 point that at certain seasons of the year, when the demand is greatest, 

 the gas is' regularly pumped from the wells into the mains. Pumping 

 was not in progress when the samples were taken. 



Determinations of nitrogen in samples collected June 6, 1898, gave: — 



(1) 1.29. 



(2) 1.28. 



7. Another well on the same farm at Murraysville yields gas exclu- 

 sively from a sand about 100 feet deeper. Gas collected on the same 



