“The use of this latter-type spirometer is depicted in figure 3. The combustion chamber, A, and motor-blower, C, are connected with the fittings at the bottom of the spirometer. The air is conducted from the combustion chamber through the pipe, b, with it “metal-to-metal” connections, is forced upwards through the soda-lime in the can, B, and passes into the spirometer bell, D, and then down around the soda-lime can and out through the fitting coneecting directly with the blower, C.” Taken from Benedict G, Fox EL. A method for the determination of the energy values of food and excreta. pg 795. Publication unknown.
From McClendon JF, Anderson HC, Steggerda FR, Conclin C, Whitaker M. A simple respiration apparatus for determination of oxygen and carbon dioxide in indirect calorimetry. Journal of Biological Chemisty, 1928; 77: 413-420.