248 INFLUENCE OF FOOD PBESERV ATIVE8 ON HEALTH. 



the withdrawal of the preservative. For instance, the average nitrogen 

 balance of the four series of observation (excluding Series II), during 

 the fore periods is 0.964, during the preservative periods 1.02, and dur- 

 ing the after periods, 1.69 grams per day. Expressed as a percentage* 

 the combined data show an excretion of 94.5 per cent of nitrogen taken 

 in the food during the fore periods, 94.1 per cent in the preservative 

 periods, and 90.3 in the after periods. 



The general summary of all the experiments with borax and boric 

 acid indicates the largest elimination of nitrogen in the fore periods, 

 an intermediate amount in the preservative periods, and the smallest 

 elimination in the after periods. 



This relation is either produced by causes other than the adminis- 

 tration of the preservative or the effect of the preservative continues 

 after its administration has ceased and even after the preservative 

 itself has ceased to be excreted from the body. It is not impossible 

 that such an influence may be exerted. The retarding influence of the 

 preservative probably increases with the length of the experiment, 

 especially in those cases in which the amount of preservative admin- 

 istered is progressively increased. When the administration of the 

 preservative is discontinued the elimination of nitrogen is probably at 

 the lowest point (if depressed by the preservative), and yet during the 

 first days of the after period (at least while the preservative is still in 

 the system) the amount of nitrogen eliminated is probably as low as 

 on the preceding days. There may be a tendency of the preservative 

 in the large amounts in which it is administered to increase the forma- 

 tion of difficultly soluble compounds of nitrogen, and by that means, if 

 no other, retard its elimination from the body. 



THE EFFECT OF THE PRESERVATIVE UPON THE METABOLISM OF 



PHOSPHORIC ACID. 



A study of the data relative to the influence of boric acid and borax 

 upon the metabolism of phosphorus reveals many contradictory results. 

 When, however, all the data are collected into one expression it is 

 found that the influence of these bodies added to the food is distinctly 

 marked on the metabolism of phosphorus and phosphoric acid. There 

 is a distinct tendency shown by them to increase the quantity of phos- 

 phoric acid excreted during the period of the administration of the 

 preservative. In the combined data of Series I, III, IV, and V the 

 average per cent of phosphoric acid taken in the food eliminated 

 during the fore periods of observation is 97.3, during the preservative 

 periods 103.1, and during the after periods 97. 



INFLUENCE OF THE PRESERVATIVE UPON THE ELIMINATION OF FAT. 



The influence of boric acid and borax upon the metabolism of fat 

 is not very marked. There is a slight tendency shown to decrease the 



