SULPHUROUS ACID AND SULPHITES. 935 



SULPHUR BALANCE. 



A study of the metabolism of sulphur in this series is of special 

 interest because it treats not only of the organic and inorganic sul- 

 phur ingested in the foods, but also of sulphur in the form of sulphur- 

 ous acid and sulphites administered as the preservative. The changes 

 through which the sulphurous acid passes, and the final. form in which 

 the added sulphur is excreted are of importance. Assuming that the 

 sulphur added to the foods in the form of sulphurous acid and sul- 

 phites would all appear in the feces and urine, we expect to find a 

 strongly negative balance during the preservative period. 



The sulphur balances are calculated in two ways. A balance is 

 made first, taking into consideration the sulphur in the food only, and 

 the second balance considers in addition the sulphur administered in 

 the form of sulphurous acid or sulphites. It is evident that the first 

 balance would be largely negative, its increase over the normal bal- 

 ance, assuming the metabolic functions to continue normal, being the 

 amount of sulphur ingested as the preservative. In the balance 

 which takes into consideration the sulphur of the preservative, the 

 presence of a minus balance indicates a tendency on the part of the 

 preservative to increase the elimination of sulphur. 



INDIVIDUAL DATA. 



The quantity of sulphur in the food administered to No. 1 in the fore 

 period is 1.303 grams daily, and it is almost exactly the same in the 

 after period. During the preservative period the average amount is 

 about 0.08 gram per day less. In the feces the quantity of sulphur 

 excreted in the fore period is 0. 1 35 gram, in the preservative period 0.115 

 gram, and in the after period 0.078 gram. It is evident from these 

 data that none of the sulphur added to the food as sulphurous acid 

 appears in the feces. On the contrary, there is a tendency to diminish 

 the sulphur in the feces, and this tendency is very marked in the after 

 period. The quantity of sulphur appearing in. the urine in the fore 

 period is 1.133 grams, in the preservative period 1.433 grams, and in 

 the after period 1.169 grams. In this case it is evident that the large 

 increase in the excretion of sulphur in the urine in the preservative 

 period and the small increase during the after period are due solely 

 to the sulphur added in the form of sulphites. The activity of the 

 kidneys in excreting the products of the added sulphurous acid and 

 sulphites is shown in a marked degree in the percentage of sulphur 

 excreted in the urine, which is 86.90 in the fore period, 117.26 in the 

 preservative period, and 89.41 in the after period. The balance in 

 the fore period is positive and its magnitude is 0.035 gram. In the 

 preservative period the first balance, considering the food sulphur only, 

 is negative, and its magnitude is 0.326 gram; the second balance, 



