BORIC ACID AND BORAX. 17 



balance of the daily rations in Series V. Its disregard during the 

 twelve days of Series IV when capsules were introduced experiment- 

 ally in no way affects the results. 



In the administration of the preservative small quantities were first 

 given, approximately as much as would be consumed in eating foods 

 preserved with borax, such as butter and meat. These quantities 

 were progressively increased for the purpose of reaching, if possible, 

 the limit of toleration of the preservative by each individual. For 

 each variation of the quantity given a separate study of the digestive 

 processes as influenced by the preservative was made. 



At the end of the "preservative period " the " after period " began. 

 During the "after period" the same quantities of food were given as 

 in the preservative period, the preservative, however, being omitted. 

 The object of this "after period" was to restore the individual as 

 nearly as possible, if there had been any disturbance of his physical 

 state, to the condition precedent to the beginning of the "preserva- 

 tive period." 



During the entire time from the beginning of the " fore period" to 

 the end of the "after period" the foods were weighed or measured 

 and analyzed and the excreta collected and analyzed. 



DURATION OF THE EXPERIMENTAL STAGES. 



The first decision in regard to the duration of the experimental 

 work was largely empirical. The one object which was sought to be 

 obtained was to make it long enough to reach reliable conclusions. 

 The effect of the duration of the test was considered of paramount 

 importance, inasmuch as it is evident, assuming that deleterious or 

 favorable effects are produced, that they would not become fully 

 manifest without a sufficient lapse of time. If the preservative in 

 question be given in very large quantities, immediate effects, either 

 favorable or unfavorable, will be noticed. If, on the other hand, it 

 be deemed desirable to begin with quantities approximating those 

 which would be secured b}^ eating foods preserved therewith, a longer 

 time would probably elapse before any noticeable effects would be 

 produced. 



A period often days as a "fore period," in order to secure the equi- 

 librium of the body, has proved to be a reasonably satisfactory one. 

 In the earlier experiments tjie period during which the preservative 

 was given was also fixed for ten days, or approximately so. Experience 

 showed that this was not a sufficiently long time. Fifteen or twenty 

 days at least should be allowed for such observations. Especially 

 is this the case if the preservative be given in increasing amounts, as was 

 done throughout most of the investigations here described. A con- 

 venient division of the time is into four-day periods, the increases in 

 the dose of the preservative to come at the end of each four days. 

 4242 No. 84, pt 104 2 



