From a series of careful measurements and special tests the following apparent volumes for different parts of the system have been calculated: Liters. Volume of the chair calorimeter chamber (without fixtures) 1360.0 Permanent fixtures (5); chair and supports (8) 13.0 ------ Apparent volume of air inside chamber 1347.0 Air in pipes, blower, and valves to surface of acid in first acid vessel 4.5 ------ Apparent volume of air containing water-vapor 1351.5 Air above surface of acid in first sulphuric-acid vessel and potash-lime can 16.0 ------ Apparent volume of air containing carbon dioxide 1367.5 Air in potash-lime can, second sulphuric-acid vessel and connections, sodium-bicarbonate cans, and pipes to calorimeter chamber 23.5 ------ Apparent volume of air containing carbon dioxide, water, oxygen, and nitrogen 1391.0 These volumes represent conditions existing inside the chamber without the subject, _i. e._, conditions under which an alcohol check-test would be conducted. In an experiment with man it would be necessary to deduct the volume of the man, books, urine bottles, and all supplemental apparatus and accessories. Under these circumstances the apparent volume of the air in the chamber may at times be diminished by nearly 90 to 100 liters. At the beginning of each experiment the apparent volume of air is calculated. RESIDUAL ANALYSES. CALCULATION FROM RESIDUAL ANALYSES. The increment in weight of the absorbers for water and carbon dioxide and the loss in weight of the oxygen cylinder give only an approximate idea of the amounts of carbon dioxide and water-vapor produced and oxygen absorbed during the period, and it is necessary to make correction for change in the composition of the air as shown by the residual analyses and for fluctuations in the actual volume. In order to compute from the analyses the total carbon-dioxide content of the residual air, it is necessary to know the relation of the air used for the sample to the total volume, and thus we must know accurately the volume of air passing through the gas-meter.