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

CHAPTER XI . MULTIPLE DISTILLATION. (A) GENERAL PRINCIPLES. 1. In the foregoing chapters we have been considering sea water distillation in its simplest form—i.e., the evap- oration or conversion of the water contained in sea water into steam, and the condensation or re-conversion of such steam into pure water. This is what is called single dis- tillation. We have also considered the subject in a slightly extended form—viz., that of double distillation— for the purpose of steam ships, by the introduction of an evaporator, but the evaporator has been used more in the nature of a boiler—i.e., a boiler worked by steam heat instead of the ordinary furnace usual with boilers. The gained steam, or steam generated by the evaporator has alone been counted for use, and the heat imparted by the primary steam by its re-conversion into water has been counted against the quantity of sea water evaporated, much as one would count the weight of coal consumed by a boiler against the weight of water evaporated. Up to the present we have not regarded double distillation (which is the first step in multiple or compound distilla- tion) in the light of so much distilled water—i.e., primary and secondary water combined—as the emanation of so much fuel consumed. 2. It is proposed now to deal with “ compound or “ multiple ” distillation, which accommodates itself to