“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.