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

172 SEA WATER DISTILLATION. use on land by having successive distillations—that is, a series of distillations linked together by means of the introduction of evaporators between the boiler (in which the fuel is consumed, and the initial steam is produced), and the condenser, in which the final steam is condensed. 3. The successive distillations are best named by the number of distillations carried out. Thus, a boiler simply discharging its steam into a condenser is obviously a single-process distillation, and is termed “ single ” dis- tillation. The introduction of one evaporator between the boiler and the condenser involves two distillations (1st, the boiler, and 2nd, the evaporator), so as to make a double process of distillation, which is consequently termed double distillation ; the introduction of two evaporators with the boiler so linked as to produce three successive distillations is termed “treble” distillation, and so on, according to the number of distillations. Properties of Steam Reconsidered. 4. On considering the various types of distilling appar- atus, it will be seen that the properties of steam apply to multiple distillation in the same way as they do to the double distiller of the steam ship, both as regards time, rate, and economy of production—i.e., as against fuel consumed. 5. It should, however, be mentioned that although the distilling machinery supplied by various makers may differ somewhat in matters of detail, as to manner of construc- tion, &c., yet on matters of principle, all are naturally governed alike. Thus, the properties of steam, as to its pressure, and heat, necessarily govern all systems of