202 University Geological Survey of Kansas. 
coal. All of this is in favor of the gas, and preference for it 
should be given when the two kinds of fuel are compared. 
It is common with the practical, every-day man to say that 
20,000 cubic feet of gas equal one ton of coal in heat value. It 
will be seen that in order to make this true where perfect com- 
bustion of coal is obtained we should have a coal producing 
only 9800 British thermal units per pound. It is probable, 
therefore, that with many furnaces wherein coal combustion 
is very imperfect 20,000 feet of gas will produce as much 
steam, or aS much heat, as a ton of coal, but for stationary 
boilers supplied with good furnaces the amount would range 
from 23,000 to 25,000. 
Another consideration of no small importance, and yet one 
which is entirely overlooked by most purchasers of gas, is the 
matter of pressure at which gas is measured. It is now cus- 
tomary in most places in Kansas to sell gas by meter measure- 
ment. Probably more than two-thirds of the customers pay no 
attention whatever to the matter of pressure at time of meas- 
urement, many of them perhaps not even knowing that this is of 
any importance. Gas-meters are constructed in such a way 
that gas is measured by volume. It is well known that if the 
pressure of any gas be doubled its volume will be halved. If, 
now, one should buy a thousand cubic feet of gas measured at 
the pressure of one atmosphere and a second thousand feet 
measured by the same meter at two atmospheres, the second 
thousand feet would be nearly, if not quite, double the first in | 
actual value, and would expand to 2000 feet if the pressure 
were reduced to one atmosphere. Within the limits of our gas- 
field the atmospheric pressure is usually somewhere between 
fourteen and fifteen pounds per square inch. If a large manu- 
facturing establishment should contract for gas to be measured 
at fifteen pounds above the atmosphere it would get nearly 
double the amount of gas that would be charged to it if it were 
measured almost at the atmospheric pressure. 
In most of our cities, towns and villages where gas is used 
for domestic purposes it is measured at about four ounces 
above atmospheric pressure. If, now, the same were measured 
to them at about fifteen pounds pressure, they would get prac- 
tically double the amount. 
The Pittsburg Meter Company, of East Pittsburg, Pa., has 
prepared a table showing what multiplier ought to be used for 
gas measurements above eight ounces in order to bring the 
