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

46 SEA WATER DISTILLATION. 22. From the above three cases, the following points should be noted :— First.—That in all three cases there was owfeide the coil the same “ sensible ” heat of 212°, and the same " latent ” heat of 966 units, that being the heat required to convert the 1 lb. of water into steam at atmospheric •pressure. Secondly.—That in all three cases the heat mside the coils was different—that is, the “ sensible ” heat not only increased as each pressure got higher, but got higher in the ratio of 1, 2, and 4, as regards the amount of sensible heat above that outside the coil. Thus— Sensible heat of 10 lbs. pres, steam = 239 - 212=: 27 units „ 25 lbs. „ =266- 212= 54 „ „ 75 lbs. „ = 320- 212—108 „ so that 54 is double 27, and 108 is double 54. Thirdly.—That in all three cases the “ latent ” heat, inside the coil, decreased as each pressure got higher, and decreased in nearly the ratio of 1,2, and 4, as regards the latent heat outside the coil. Thus— Latent heat of 10 lbs. pres, steam = 966- 946 20 units. „ 25 lbs. „ = 966- 927--39 „ „ 75 lbs. „ — 966- 889—77 „ i.e., 39 is (nearly) double 20, and 77 is (nearly) double 39. 23. The outcome of the foregoing observations is that the primary steam is capable, as we should expect in theory, and as we find in practice, of imparting its “ sens- ible ” heat in proportion to its intensity above that of sea water, to which it imparts its heat. Therefore (other conditions being kept to), steam at 25 lbs. pressure is capable of evaporating (in point of time) twice as much