Category Archives: Basal metabolism

Dethloff’s Spirograph, 1926

From “Methods in pulmonary physiology”, by Bertels H, Bucherl E, Hertz CW, Rodewald G, Schwab M.  Translated by Workman JM. Hafner Publishing Co., 1963, page 24.

“In Dethloff’s apparatus, the difference in volume of expiratory gases before and after absorption of CO2 is used to measure CO2 output.  To this end two gas meters are placed in the circuit, one proximal and one distal to the CO2 absorber.  The difference in reading between the two gas meters provides a continuous measure of CO2 output.”

Fleisch Metabograph, Diagram, 1955

From “Methods in pulmonary physiology”, by Bertels H, Bucherl E, Hertz CW, Rodewald G, Schwab M.  Translated by Workman JM. Hafner Publishing Co., 1963, page 42.

“Figure 42. is a diagrammatic representation of the construction of the apparatus. A motor (M) drives the pump (31), which sends air int the CO2 abdorbant chamber (42).  Freed of CO2, the air passes by way of the tube (33) into (21), then under the valve (19).  From here it is led through tubes (22), (17), (14), (15), (30) and returns to the pump (31).  During inspiration the bell (9) of the double spirometer sinkes and a corresponding volume of air passes out of (I) through tubes (12) and (14) into the lungs, while the pump removes an equal volume from the chamber (E) through tubes (11), (30).  During expiration, the volume of air that leaves the lungs travels by way of (15) and (11) to chamber (E), while the corresponding volume passes into chamber (I) through (17) and (12).  This the bell (9) rises.  The partitioning septum (10) is pierced by a small opening so that some air is always passing from chamber (I) into chamber (E), preventing accumulation of CO2.

“Volume stabilization is achieved through an electrical contact (7).  When contact is broken, oxygen is added to the system by a pump through (26).  This establishes the bell in the middle position, and maintains the O2 concentration in the system practically constant.  When the bell touches the contact (7), the total volume of the system is 32 liters.

“In the absorption chamber (42) there are rotating discs, over which KOH runs.  This arrangement provides the larges possible surface area for CO2 absorption.  The KOH is collected in a sump (43), removed hence by a pump (39) and sent back to the distribution chamber (34) by three parallel routes (38), (37) and (36).  Recording of CO2 production is based on the measurement of the electrical conductivity of the KOH.  Throughout the period of study the conductivity of the KOH is held constant.  When the degree of alkalinity of the KOH is reduced by the expired CO2 resulting in reduced conductivity, fresh KOH is added through the side tube (32) until the original conductivity is restored.  Thus the CO2 production of the subject under study is determined directly by the amount of fresh KOH that has been added.”


Measuring gas exchange, 1911


Using a Chauveau valve, the subject’s exhaled volume is measured by a gas meter and analyzed for CO2 and O2 chemically.  Found in “The Human Motor, Or, The Scientific Foundations of Labour and Industry” by Jules Amar, Elsie Mary Butterworth, George E. Wright, published by G. Routledge & sons, Limited, 1920, page 145, but was ascribed to Jules Amar, Journal de Physiologie, March 1911, page 212.

Douglas Bag, Basal Metabolism, Sheep, 1964


From “The Energy Exchange of Ruminants” a PhD thesis paper by John Patrick Joyce for the University of Glasgow, 1964, page 28.

“Photograph of outdoor experimental site demonstrating the collection of sheep by when wearing a face mask.”

“A large pit 9 ft x 4 ft x 1 ft 6 inches was dug just in front of the skeleton framework and was lined with wood. This pit acted as a guard for two large Douglas bags when they were being filled by the animal and prevented them from blowing away. Placing the Douglas bags below ground level also ensured they did not act as a wind shelter for sheep, especially when the bags were filled with exhaled air.”