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

24 SEA WATER DISTILLATION. salinity of sea water and brine by 32nds of “ density ” (which is how it is commonly expressed) may be made clearer by the following illustration. Fig. 1 shows a hollow cube, the inside dimensions of which are 1 square foot at its base, and extending upwards for rather more than 1 foot. If pure water be now poured in, so that the quantity reaches to the height of 1 foot, we have obviously 1 cubic foot of pure water. If some insoluble matter (say sand) be added to this 1 cubic foot of water, the water will be displaced to the same extent as the volume of the sand that is added, and will rise to a cor- Fig. 1. responding height above the I foot level. If, however, instead of sand, common salt (which is soluble in water) be added to the cubic foot of water, this will make no difference in the level of the water by displacement, but as additional substance has been added, the addition must manifest itself somehow, and it does so by making the same volume of water more saline and denser by the quantity of salt that has been added and become dis- solved in the water. The saline water is still, therefore, only 1 cubic foot in volume, but its mass and its weight are increased. If double the quantity of salt be added,