Insensible Perspiration. 



115 



Table 46. Insensible perspiration during work and rest* Continued. 



[Quantities per hour.] 



1 Experiments Nos. 1 to 22 are for mental work. See U. S. Dept. of Agr., Office of Exp. Stas. 

 Bui. 208, 1909. 



it is seen that the insensible perspiration from this subject was 1049 -+- 136 

 684 188 = 313, or an insensible loss amounting to 313 grams in 7 h 15 m . 

 This is at the rate of 43 grams per hour. It frequently happened in the short 

 experiments that the change in body-weight gave the insensible loss directly. 



Fluctuations in the Insensible Loss. 



Obviously, muscular activity would materially alter the insensible loss since 

 there would be a marked increase in the water given off and the carbon dioxide 

 produced. For the purpose of securing and comparing normal data, therefore, 

 the results have been tabulated chiefly for rest experiments. These results 

 are shown in table 46 herewith. The very marked influence of muscular 

 activity upon insensible loss is well shown in the few work experiments here 

 given, which are included for that sole purpose. The remaining experiments 

 in the table were all made with subjects at rest and the averages and deductions 

 are drawn entirely from these. 



Influence of relative humidity. It is observed that frequently with the same 

 subject, even excluding muscular exercise, there is considerable variation in 

 the insensible perspiration per hour. These fluctuations are often easily ex- 

 plained by the relative humidity of the air. In the rest experiment, No. 60, 

 for example, there were 3 days in which the ventilating conditions varied 

 markedly from day to day. On the first day the subject wore a mask by means 



