572 



JOHN R MURLIIST 



As a means of studying the heat production of man the second method 

 has heen employed in the form of a bath in which the subject could be di- 

 rectly immersed. The first to use this method at all successfully was 

 Liebermeister (#), but his technique was subjected to very severe criticism 

 a few years later and the method fell into disfavor until rescued by Le- 

 fevre^) in 1804. The chief objections to Liebermeister's method were: 

 (1) that he used too large a volume of water, (2) that he read its tempera- 

 ture on only a single thermometer and (3) did not guard against stratifica- 



Fig. 24. The air calorimeter of Lefevre. GOO, wall of the chamber; T, ther- 

 mometer for measuring the temperature of the atmosphere after it has passed over 

 the subject; e, e, baffle plates for distributing the air as it enters; F, G, II, baffle plates 

 to prevent channeling of the air as it leaves the chamber; A, the aspirator; C, covering 

 for the head which prevents radiation of heat to the exterior. 



tion of the water. Lefevre overcame these objections and proved that the 

 heat production of a man could be measured with a high degree of accuracy 

 by this very simple method. Even the heat of vaporization of water which 

 ordinarily is lost through the lungs can be compensated by having the bath 

 at 35 C. in which case the subject respires an atmosphere already satu- 

 rated with moisture. 



One of the simplest types of compensation calorimeters is that of Le- 

 fevre (e) designed for measurement of the heat production of a man by 

 carrying away the heat of his body just as rapidly as produced with a cur- 

 rent of air. The calorimeter consists of a zinc chamber 3 meters long, nar- 

 row at the two ends, but broader in the middle where the subject sits On a 

 stool (Fig. 24). Air is drawn through the chamber by means of an aspira- 

 tor shown at A. The volume of air is recorded by means of an anemometer. 



