Carbon in Urine. 



383 



In only one of the several fasting experiments previously made in tins 

 laboratory n was the carbon determined in the urine. In experiment No. 36, 

 which lasted one day there were 8.54 grams of carbon excreted and 11.34 grams 

 of nitrogen. The ratio was C : N = 0.753. 



The method of determining the carbon in urine at present in use in this 

 laboratory is as follows : Five or 10 cc. of urine (the amount depending upon 

 the specific gravity) is drawn into an aluminum dish and evaporated nearly to 

 dryness in a vacuum desiccator. The partially dried mass is transferred from 

 the aluminum dish to a copper combustion boat and dried again, prior to 

 combustion in the Liebig combustion tube. In this process there is unques- 

 tionably a loss of nitrogenous and carbonaceous material, which it has as yet 



Note. It is important to note that in all three experiments, the ratio is above unity 

 only on the fifth day of Cetti's fast, and the author distinctly questions the accuracy of the 

 determination for that day. 



been impossible to prevent. The method does, however, give as high results 

 for carbon as any method with which we are familiar and consequently it has 

 been used in all the experiments here given. 



The total quantity of carbon and the total nitrogen excreted daily in the 

 urine together with the ratio of carbon to nitrogen are given in table 202. It 

 should be remembered that in experiments Nos. 59 and 68, the apportionment 

 of the carbon over the different days was made according to the nitrogen elimi- 

 nation, and hence only the ratio for the total excretion for each experiment can 

 be used. In all the other experiments, the carbon was determined for each 

 day and hence the daily ratios may properly be used. 



The lowest carbon elimination in any experiment was on the first day of 

 experiment No. 71, 5.22 grams, while the highest was on the fourth day of 

 experiment No. 77, 14.57 grams. Both these experiments were with the same 

 subject and thus they serve to show the wide variations that may occur in the 

 carbon elimination in the urine of a fasting man. The most striking variation 

 in any one experiment is seen in experiment No. 77, when on the first day the 

 elimination of carbon was 7.97 and on the fourth day, 14.57 grams. In consid- 

 ering the long experiments, it is noteworthy that the carbon elimination is 

 invariably lowest on the first day and on the remaining days is relatively 



61 U. S. Dept. of Agr., Office of Expt. Sta. Bui. 136 (1903), 



