In addition, corrections are made to C02 and 02 values on the basis of the initial and final composition of chamber air at STP. Chamber volume, including ancillary equipment, is about 130 1. Heat production is estimated, without correction for urinary nitrogen, using the equation of Romijn and Lokhorst (1964). Moisture output by the fowl can be determined from the increase in weight of the1 1. flask(S) and the calcitum chloride train (T) during the period of measurement of respiratory exchange. A correction is then applied to the weight of water found on the basis of any change that occurred in the relative humidity within the chamber.