INFLUENCE OF FOOD PRESERVATIVES AND ARTI- 

 FICIAL COLORS ON DIGESTION AND HEALTH. 



II. SALICYLIC ACID AND SALICYLATES. 



ORGANIZATION OF THE EXPERIMENT. 



The researches to determine the effect of salicylic acid upon diges- 

 tion and health were carried on in the same manner as those described 

 in the first part of this bulletin on boric acid and borax. Some few 

 changes were made in the methods of manipulation, sampling, and 

 analysis in order to simplify the process and to save time. Instead 

 of the analysis being made upon each daily sample of the food or f eces, 

 a careful study of composite samples for the various periods was made 

 and the analysis of the composite sample for the period accepted as a 

 true representative composition of the food or excrement during that 

 s period, it was found also, in so far as the labor and time were con- 

 cerned, that it was just as convenient to have all twelve of the subjects 

 under observation at once as to divide them into squads of six each and 

 alternate the periods of observation of each squad with periods of rest. 

 For example, in the analysis of the bread for the tables the daily 

 samples were composited and the analyses made for twelve persons as 

 easily as for six. The same is true for each article of diet and for the 

 analysis of the excrementitious material. By this arrangement the 

 analysts were able to complete the analytical work during the periods 

 of recreation and to devote more time to the classification and tabula- 

 tion of the data. The burden of the analytical work was thus dimin- 

 ished one-half, while its accuracy and efficiency were not sacrificed in 

 any respect, but on the contrary rather increased. 



The analyses of the foods and feces were made in the Division of 

 Foods under the supervision of W. D. Bigelow; the conduct of the 

 food table, the study of the body weights, and the urinalyses were 

 under the charge of F. C. Weber, and the microscopic tests were con- 

 ducted by B. J. Howard. 



Owing to other arrangements the surgeons in connection with 

 the Marine Hospital Service found themselves unable to give the 



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