Liquid Air: Air Compressed to 170 Atmospheres and Expanded through the Hampson Liquefier (Travers 1901)

Air freed of carbon dioxide and water is pumped to about 170 atmospheres and let out through a fine valve at the foot of long copper coils. The expanding air cools a little and flows back over the coils, cooling the air coming down, until some of it turns liquid and drips into a vacuum vessel. Result: liquid air, about 1-1.5 litres an hour, the first after about four minutes. Source: M. W. Travers, The Experimental Study of Gases (1901), pp. 190-194, Fig. 100 (shown above). High pressure and liquid air: Travers warns that a sudden fault can cause a serious accident.