Abstract
The essential parts of the calorimeter are: (a) a tank containing about 300 litres of water; (b) 2 cylindrical spirometer domes in the tank, the capacity of each being 100 litres and height 1 meter; (c) a tank containing 5 kilos of 4 mesh soda lime connected with each spirometer with a 3-way valve; (d) a glass tube of 2.5 cm. bore shaped like the Greek letter π, one end of the horizontal portion being the mouth piece, the other closed by a rubber stopper at the moment the experiment is to begin, and the 2 vertical portions fitted with 4 cm. lengths of Visking sausage casings (to act as valves) and connected by rubber tubing to the 3-way valves. Each spirometer dome is counterbalanced by a weight fastened to a bicycle chain passing over a large bicycle sprocket wheel. The thickness of the wall of the dome is such that the weight of water displaced equals the weight of the chain. A meter stick is used as a scale and each mm. corresponds to 100 cc. A thermometer is inserted in each spirometer dome. The tube leading from the 3-way valve up through the water into the spirometer has a large enough surface to bring the air passing through it to the temperature of the water and this tube in spirometer No. 1 contains a wick to saturate the air with moisture.
In operation, spirometer No. 1 is filled with outdoor air (the CO2 of which is considered negligible), the temperature recorded and spirometer No. 2 left empty, the mouthpiece adjusted to the patient and the breathing watched. At the end of an expiration the rubber stopper is inserted and stop watch started.
Get full access to this article
View all access options for this article.