Wood, 20 per cent. H.O. $ 5.00 per cord 0.167 2.3 7,620 Bitu. coal $ 4.25 per ton. 0.213 7.5 16,009 Ant. coal $12.50 per ton 0.625 6.0 4,354 Gasoline, sp. gr. 68 $ 0.14 per gallon, 5⅔ pounds. 2.470 10.0 1,846 Kerosene, sp. gr. 80 $ 0.11 per gallon, 6⅔ pounds. 1.650 10.0 2,753 Coal gas, 1.50 per 1000 cubic feet. 3.100 20.0 2,927 Alcohol, 90 per cent., 50 per gallon, 7.140 6.4 404 7 pounds Electricity, 0.15 per kilowatt-hour 57.4 The relatively high heat value of Blau gas (1704 B.t.u.) and the fact that it may be reduced to a liquid form for transportation has resulted in the manufacture of small lighting plants that may be used in places where other forms of liquid or gaseous fuel are not desirable. For transportation the gas is compressed in seamless, steel bottles that contain about 20 pounds of liquid. The charged bottles are shipped to the consumer and when empty are returned to the manufacturers to be refilled. The entire plant--ready to be attached to the distributing pipes in the house--is contained in a steel cabinet. The charged tanks are attached to a larger tank into which the liquid gas is first expanded. This expansion is accomplished by an automatic valve that maintains a constant pressure in the large tank. With this plant the lamps and burners of the stoves are operated as with city gas--no generating or preliminary preparation being necessary. As soon as the bottles are exhausted they are replaced by others and the empty bottles are shipped to the factory to be refilled. =Measurement of Gas.=--When gas of any kind is purchased from a manufacturing company, the amount used is measured by a gas meter, located at the point where the gas main enters the building. The readings of the meter are taken by the company at stated intervals and the amount registered is charged to the account of the consumer. Gas is sold in cubic feet and is so registered by the meter. The price is quoted by the manufacturers at a definite rate per thousand cubic feet. The difference between the last two readings of the meter furnishes the amount from which the gas bill is reckoned. The occupants of a building are responsible for all gas registered by the meter and, therefore, should be acquainted with the conditions under which the gas is sold. Gas bills are often the subject of dispute because of failure to understand the period of time covered by the amount claimed; again, the varying length of days due to the season of the year has a pronounced effect on the amount of gas consumed. Lack of care in the economical use of gas is probably the most prolific cause of disputed bills.