A Practical Manual On Sea Water Distillation
With A Description Of The Necessary Machinery For The Process

GAS AND OIL STOVES FOR EVAPORATORS. 169 (5) The circulation water can be drained out at (J) when leaving off work. (6) The pure water escaping at (E) is usually warm for industrial purposes, but when required for drinking, is cooled and rendered palatable by being passed through a suitable filter placed under (E). 4. The consumption of gas during work may be ascer- tained as follows :— (1) In Chapter v. on “ Fuels” it was shown that town gas was capable of imparting heat at the rate of 570,000 to 600,000 B.T.U. per 1,000 cubic feet of gas consumption. Therefore, to heat 1 lb. of water from, say, 60° to boiling point (212°) would require 152° (212- 60=152), to which must be added the latent heat which lias to be absorbed by that pound of water to convert it into steam ; hence, a total of 1,018 B.T.U. (152+966= 1,018) of heat is re- quired to produce 1 lb. weight of steam. Every 1,000 cubic feet of gas will, therefore, evaporate from 560 to 588 lbs. of water into the same weight of steam, which can then be re-converted into the same quantity of dis- tilled water. At 3s. per 1,000 cubic feet, the cost of obtaining 500 lbs. of distilled water (i.e., 50 gallons) would be about 0’7 of Id., which is rather less than fd. per gallon. (2) In the foregoing calculation, no allowance whatever is made for unavoidable loss, or rather waste of heat— that is, gas consumed that has not imparted its heat to the work it was put to. It is difficult to estimate what that waste is, but assuming it reaches the large amount of 40 to 50 per cent., the cost of producing the above distilled water would still not exceed l|d. per gallon.