Feces. 521 



was computed from the proximate analysis, there was a very decided discrep- 

 ancy between the computed heat of combustion and that actually found by 

 determination with the bomb calorimeter, and the per cent of ash was much 

 higher than ordinarily found. It thus appeared that some material of a high 

 energy content insoluble in ether was present in the feces, and by treating the 

 feces with hydrochloric acid and alcohol, large amounts of fatty acids were 

 liberated from the very considerable quantity of soap present. After this pre- 

 liminary treatment with hydrochloric acid and alcohol, the feces were dried 

 and again extracted and the percentage of fat was increased enormously, so 

 much, in fact, that the sum of the percentages of water, protein, fat, and ash 

 was more than 100 per cent. This, of course, eliminated all carbohydrates and 

 further showed that the determination of one of the constituents was slightly 

 too high. A consideration of the quantity of ash in the feces showed that this 

 was unusually large. Since the modified method for fat determination had 

 shown the presence of a large amount of soap, in the absence of definite ash 

 analyses, it was assumed that the soap present was combined with calcium, and 

 when charred the calcium remained in large part in the form of calcium 

 carbonate, which would hold carbon dioxide at the low temperature of incinera- 

 tion of ash and thus yield a result for the percentage of ash higher than should 

 be obtained. On the basis of this assumption it was decided to estimate the 

 ash by difference and hence the sum of the percentages of water, protein, and 

 fat deducted from 100 per cent was taken as the percentage of ash. 



Unfortunately, the presence of this large proportion of calcium soap in the 

 feces was not discovered until the samples of feces from some of the experi- 

 ments had been entirely used in making different determinations, so that it 

 was necessary in some instances to assume a percentage of fat based upon the 

 marked increase in the ether soluble material of other samples after treatment 

 with hydrochloric acid and alcohol. 



The feces belonging to metabolism experiment No. 74 gave, on analyses 

 by the method ordinarily used : For sample No. 3838, 9.06 per cent protein, 

 4.41 per cent fat, 7.93 per cent carbohydrates, 3.52 per cent ash, with a heat 

 of combustion of 1.533 calories per gram; for sample No. 3839, 6.54 per cent 

 protein, 3.28 per cent fat, 15.90 per cent carbohydrates, and 6.77 per cent ash, 

 with a heat of combustion of 2.016 calories per gram. 



After experience had shown that by the new method of analysis a larger 

 percentage of fat was obtained in the feces for experiments No. 70 and No. 76, 

 it was thought advisable to treat these two sample of feces by the same method, 

 but unfortunately both samples had previously been exhausted. It seemed 

 reasonable to suppose, however, that the determinations of fat in these two 

 samples as originally made were too low, and that this was the case seemed to 

 be borne out, particularly in sample No. 3839, not only by the high ash content 

 but also by the fact that their heats of combustion by calculation varied very 

 widely from those actually obtained. 



