THE GAS COALS OF OHIO. 749 
The value of coal gas as an illuminant is enhanced or diminished 
as the per cent. of olefiant gas is increased or decreased. 
With the generally reduced prices of gas, a very large consumption 
is now being caused by the use of gas cooking stoves and gas engines, 
and in this connection it will be of interest to give the heating power 
of theidifferent gases, as found in the tables compiled by Dr. Letheby, 
leaving the non-combustible gases, nitrogen, oxygen and carbonic acid 
out of consideration : 
1 cubic foot of hydrogen gas will elevate 1° Fahr., 329 lbs. water. 
1 (<3 66 marsh $¢ (3 (%3 996 66 
Loy Sf “ ~ olefiant if “ “1,585 
t “ carb. oxide “ G5 GS se 
ea ns ‘¢ common coal “ i “650 is 
| Wie “ cannel coal “ sé <6 760 ee 
