A portion of the oil distilled at the second distillation, or green oil stage, is sent from the stills to the paraffin sheds to be cooled and the scale extracted, this eventually being made into paraffin wax. Stored in tanks until brought down to atmospheric temperature, the oil is pumped into the inner chamber of a cooler, which consists of a series of four vessels having inner and outer compartments. At the same time, anhydrous ammonia is forced into the outer compartment or jacket, and absorbs heat from the cooler, freezing the oil in the inner jacket into a pasty mixture of liquid oil and solid crystals of wax. This mixture is then pumped into filter-presses, where a portion of the oil flows away through the cloth, while the wax is left behind in solid cakes, still containing a quantity of oil. These cakes are delivered by conveyors to the back of the hydraulic presses, where they are wrapped in cloth and placed on shelves between iron frames in the presses, most of the remaining oils being thus squeezed out. The material obtained from the hydraulic presses is known to the trade as paraffin scale, and as it is discoloured by the small quantity of oil which cannot be removed by pressing, a process of sweating by steaming in large brick compartments is adopted, in order to remove the oil. The scale, consequent upon the removal of the oil therefrom, becomes whiter and of higher melting point, and after further treatment is finally passed through filter paper and run into moulding trays. When cooled, this product is known as paraffin wax, of which there are many grades. One cannot enter into the technical arrangements involved, for obvious reasons, the chief one of which is that these cannot interest the reader; but sufficient has already been written in this chapter to suggest to the reader the perfection which has now been reached in the treatment of the shales of the Midlothians. As to the future, it is full of promise. There is no doubt that for many years to come the full force of foreign competition, as it has existed in previous times, will not be felt. There is a free field for Scottish enterprise in connection with the distillation of its oil-bearing shales. Nor is the region for development limited to its present area. Reports point to the fact that much area of commercial ground exists, not only on the eastern side of Scotland, but also in the north and north-west, while it is already an open secret that those responsible for the conduct of Government operations are viewing with favour even the liquid extraction of oil from certain areas not far distant from the zone of the present operations. The Scottish shale-oil industry has, so far, managed to defy competition from abroad to an extent which is reflected in the balance sheets of the several operating companies, whose yearly dividends have been from 50 per cent. downward during recent years.