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

STEAM. 49 stated as required for oufeide the coils. This will, how- ever, be more exhaustively dealt with in Chapter vi. Condensation. 29. What has been said above with regard to evapora- tion of steam applies equally (though conversely) to its condensation. Thus, the secondary steam, escaping from the evaporator at a temperature of 212° of sensible heat, is also charged with its latent heat of 966 units. If this steam has to be condensed into water, a sufficient quantity of circulation water must be supplied, not only to absorb this latent heat, in order to condense this secondary steam into secondary water, at the temperature of 212°, but also siifficient circulation water to cool such boiling hot water down from 212° to whatever temperature is specified. This matter will, however, be more fully dealt with when the chapter on the Distilling Condenser is reached. Note.—The rule that the amount of heat used to con- vert a specific quantity of water into steam is precisely the same as the amount of heat that is imparted when that steam is re-converted into water, is simply the axiom propounded by Carnot, which is, in practice, as follows :— Any substance transformed from one physical state to another, and then re-converted to its original state, so as to be identical therewith, the heat it has after re-con- version is precisely the same as it originally had. So that 1 lb. of water, at a specific temperature converted into steam, and then re-converted into 1 lb. of water at its original temperature, all the heat spent in the conversion into steam is recovered when the steam is re-converted into water at its original temperature. This is, of course, ignoring waste of heat during the process. 4