BORIC ACID AND BORAX. 233 



COMPARISON OP PERCENTAGES OF FAT ELIMINATED. 







For a general view of the influence of the preservative upon the 

 percentage of the fat eliminated it is desirable to review the data as a 

 whole. For this purpose they are collected into the following tabular 

 statement, taken from Table LXXV (p. 386): 



Per cent. 



Fore periods 4.1 



Preservative periods 4.0 



After periods . 4.2 



The data as a whole seem to indicate a very slight influence on the 

 part of the preservative in increasing the percentage of fat consumed 

 in the body. This action must be of very small magnitude, and the 

 data are so contradictory in regard to it individually that the evidence 

 as a whole must be construed with this fact kept in view. 



CALORIES. 

 BALANCE. 



It was considered that it would be of interest to study the efl'ect of 

 the added preservative upon the oxidation of the carbohydrates, fats, 

 and other oxidizable substances in the foods during their passage 

 through the body. To this end the heat-producing power of the foods 

 was determined by a combustion in an atmosphere of oxidation in the 

 usual way, and this was compared with the amount of heat-producing 

 materials left in the excreta. (See Tables LXXVI-LXXXIV.) In 

 the latter case a partial determination of the heat value was made by 

 direct combustion in the bomb for Series II, while in the case of 

 Series III, IV, and V the heat value of the urine was calculated from 

 its analysis. Numerous comparisons, however, of direct determina- 

 tion of heat value and calculation from analysis indicate that the results 

 of the two methods are sufficiently near together to serve for purposes 

 of comparison when large numbers of samples are considered. 



It is evident that where the body is neither gaining nor losing in 

 weight the calories balance represents the actual quantity of heat pro- 

 duced during the passage of the food through the body. 



No calories were determined in Series I. 



SERIES II. 



In Series II the calories were studied in the case of only three of the 

 members of the class, amj at the end of the preservative period these 

 three were also ill, so that the completion of the series by a stud} r of 

 the after period could not be accomplished. The summary for Nos. 

 7 and 10 is discussed, as No. 12 did not take the preservative through- 

 out the third subperiod. 



During the fore period in this case, January 21-27, inclusive, the aver- 

 age daily balance for Nos. 7 and 10 for the calories is 3,418.3; for the 



