8 



In the original experiment the total benzoic acid recovered (both 

 as hippuric and as benzoic acid) amounts in the case of those receiv- 

 ing benzoic acid to 81.32 per cent of the total quantity ingested, 

 while for those receiving sodium benzoate the total quantity amounts 

 to 61.41 per cent. Thus there is shown a marked tendency to restrict 

 the excretion of benzoic acid when administered as benzoate of soda, 

 the total decrease being almost exactly 20 per cent as compared 

 with the excretion of benzoic acid. It is thus seen that much larger 

 quantities of benzoic acid are retained in the system after a given 

 time when administered as benzoate of soda than when administered 

 as benzoic acid. This fact is another confirmation of what is shown 

 in so many other instances in this study of the retarded effect of the 

 preservative upon the system when administered as benzoate of soda. 



The results of the supplemental study conducted with six subjects 

 over a period of 29 days (a fore period of 5 days, a preservative 

 period of 10 days, and an after period of 14 days) and a smaller 

 ingestion of the preservative (a total of 12.5 grams) again showed the 

 slower elimination of the preservative when administered as benzoate 

 of soda. During the preservative period 93 per cent of the amount 

 ingested as benzoic acid was recovered as hippuric acid, while for 

 those receiving benzoate of soda only 72 per cent was recovered. The 

 differing conditions of the experiments, especially the decreased 

 amount of preservative and the fact that the analyses in the second 

 case were made on the daily samples instead of the composites, 

 account largely for the fact that all of the benzoic acid was recovered 

 as hippuric acid in the supplemental study. At the close of the first 

 after subperiod the entire amount of benzoic acid ingested as such 

 had been recovered, while in the case of those receiving benzoate of 

 soda only 76 per cent had been recovered. The increased excretion of 

 hippuric acid as compared with the fore period continued in the case 

 of these subjects in the second after subperiod, but only reached 77.6 

 per cent of the amount ingested. There is in this series, as in the pre- 

 ceding one, about 20 per cent less of the benzoic acid recovered when 

 it is ingested as sodium benzoate. 



The increase in the quantity of hippuric acid produced and ex- 

 creted can not be neglected in studying the effects of the administra- 

 tion of preservatives upon health and digestion. The preservatives 

 can only be regarded as foreign bodies of a toxic character which 

 the system must eliminate. The normal burden imposed upon the 

 kidneys in the excretion of the natural degradation products of 

 metabolism is quite sufficient for the preservation of their healthy 

 activity. The additional amount of excretory matter produced by the 



[Cir. 39] 



