Metabolism Experiment No. 68. 67 



Column h shows the gain or loss of body material to the body, as determined 

 from the data in the previous column of the table. Column i shows the gain 

 or loss of body-weight as found by means of the weighing apparatus. In the 

 two days of this experiment, there are discrepancies of considerable size. On 

 the first day the error amounts to over 70 grams and on the second day it is 

 about 24 grams. The difficulty of securing uniformity in the clothing worn, 

 handkerchief, contents of pockets, and other minor articles, especially in the 

 earlier experiments, renders such a discrepancy as here appears not at all 

 surprising, if it be understood that the weight of the subject when undressed 

 was obtained indirectly, i. e., by deducting from the combined weight of the 

 subject, chair, clothing, and bedding, the weight of the chair, clothing, and 

 bedding. The records, though admittedly liable to considerable error, are here 

 given. They show that the agreement is roughly approximate with the com- 

 puted gain or loss from the income and outgo. Subsequent experiments show 

 this agreement much more strikingly, but up to the present time the greatest 

 difficulty has been to secure absolute uniformity in the miscellaneous articles 

 weighed with the man. 



Another factor affecting this determination is that of the loss or gain of 

 moisture by furniture and articles in the respiration chamber. While it is 

 possible to weigh the chair, bedding, and other small articles of furniture, there 

 is a material absorption by loss of moisture from books, papers, minor articles 

 of clothing, etc., and when a relatively large number of these articles are in 

 the chamber, the difficulty in securing accurate weighings is increased. A great 

 difference is noticed among different subjects as regards the quantity of material 

 such as books, papers, etc., required during the different experiments. 



Considering all the possible errors arising, it is probably true that the 

 discrepancies between the actual weighings and the computed gain or loss may 

 in almost every instance be attributed to errors in weighing. 



Output of Heat. 



In order to simplify the explanation of the method of presenting the results 

 of the heat measurements, the data were classified in experiment No. 59 in 

 two tables one, the " Summary of calorimetric measurements and total heat 

 eliminated " ; the other, " Total heat production." In this and all subsequent 

 experiments, however, the results are combined in a single table. The sum- 

 mary data for such computations are given in table 30, in which is recorded 

 first, the heat measured in terms of C 20 ; second, the heat used in the vaporiza- 

 tion of water ; third, the sum of the other heat corrections 19 referred to above, 

 and finally, the total heat production. 



The data for this experiment, corresponding to those of experiment No. 59 



19 For detailed discussion of these corrections and methods of applying them, see 

 discussion in metabolism experiment No. 59, pp. 42 to 49. 



