Figure 1-15 Alfred Coleman's economizing device. The anesthetic gases entered the lower bag and passed into the upper bag through a one-way valve. Gases were inhaled and exhaled through the tube (h), passing over a lime container (1, 2) held in frame (k) that eliminated carbon dioxide; (c) is gas inlet. The conserved gas in the upper bag was used during a later anesthetic administration. (From Coleman A: Mr. Coleman's economizing apparatus for re-inhaling the gas. Br J Dent Sci 12:443, 1869.)