PLEASE NOTE! THIS POST CONTAINS MUCH IMPORTANT INFORMATION.
Here we see one of the two great stills - each with a capacity of 2,295 gallons.
Dallas Dhu has two stills - the wash still and the spirit still.
The stillman's job was carefully to control the heat of the stills. He also had to make sure that the wash still, containing the yeasty brew, did not overflow. The neck of the wash still contains two glass windows so that the height of the froth in the still could be monitored; if the still man saw froth in the top windows, the heat was too high.
The shape of thee still is is very important, because it is the shape that affects the character of the spirit produced; any change in shape would change the final flavour of the whisky.
The still man opened a valve to fill the wash still with wash. He gradually raised the temperature of the still while the vapour rose up the neck and out of the worm outside. The still relied on the different ingredients of the wash evaporating at different rates, allowing the alcohol and other chemicals in the wash to be separated from the water. The product from the wash still, was called 'low wines'. What remained in the still (mainly water and yeast) was called 'pot ale' and was run into the sewers!
The low wines were then distilled again in the spirit still. This produced a cleaner spirit which the brewer drew off into the spirit safe.
Just a word about the worm tubs. There were two worms - the low wine worm and there spirit worm. Two tubs held the worms, long spirals of copper pipe attached to the stills. When the stills were working, cool water was kept flowing into the tubs. As the hot vapours coming from the stills entered the worm, the cooling water condensed them so that they could flow back to the still house.