Sulphur can be isolated by______?Fill in the blank.

Frasch's process is an industrial method of obtaining sulfur from underground deposit or sea beds. It was widely used as a major method to extract sulfur till 20th century. Three concentric tubes are inserted into the crust. Super heated water is passed through the outer most tube while hot air is passed through the inner most tube. This leads to the upwelling of molten sulfur through the middle tube.