two tables in the quantities which are recovered in the urine, being remarkably low in the case of all the members of the class of Series III. No satisfactory explanation of this variation can be given. Had it occurred in only one instance it might have been attributable to a failure to collect the whole of the urine or to some analytical error, but, being uniformly low, these explanations are not tenable. Of the total quantity of boric acid given to all the members of the class, namely, 132.9 grams, 84.9 grams are recovered in the urine, a percentage of 63.88. The data for Series IV are given in Table VI. We have here a return to the percentage occurring in the urine shown in Series I and II. The highest amount recovered is in the case of No. 11, namely, 89.74, and the lowest in the case of No. 8, 78.68. During this series. 99.5 grams of boric acid in the form of borax is given in the food, of which 82.55 grams are recovered in the urine, or 82.96 per cent. The quantities of boric acid recovered in the individual cases in Series V vary greatly. (See Table VII.) As has been already explained, only-gram quantities are given during this series of observations, but the exhibition of this quantity is extended over a period of fifty days, so that in normal cases 25 grams of boric acid are administered during this period to each of the subjects. In point of fact, however, in only two instances is this full amount taken, while in a third instance within half a gram of that amount is taken. The largest percentage recovered in any one instance is in the case of No. 4, namely, 84.42 per cent. No. 4, however, completed only about half of the period. The smallest quantity excreted is found in the case of No. 3, namely, 68.44 per cent. Of the 127 grams of boric acid administered during the whole series 95.47 are recovered in the urine, or 75.17 per cent. Summarizing the quantity of boric acid given during the whole period of observation, including the five series (Table VIII), we find that it amounts to 607.4 grams. Of this quantity 468.69 grams are recovered in the urine, or, expressed in percentage, 77.16. In connection with this determination attention should be called to the fact that the quantitative determination of boric acid in a liquid like urine is attended with considerable difficulties, unless such a length of time be devoted to it as would render the execution of a large quantity of work impracticable under existing conditions. The methods employed are fully described in the part of this bulletin devoted to the methods of analysis, and it is believed that the data obtained, while not rigidly exact, are satisfactory for the explanation of the metabolic processes. The data show that the great burden of excreting the boric acid from the body falls upon the kidneys. In order to determine whether boric acid was lost to any extent by perspiration, one of the assistants in the laboratory carefully extracted with water a set of flannels worn for one hour during a game of ten nis on a hot day. Before the game he had carefully bathed and put on a clean suit of flannels. As a result no boric acid could be detected. Two further trials were made for a longer period of time. The men undertaking them bathed, put on clean suits of flannels, and wore them for a period of twenty-four hours. During this time they played tennis for several hours, and rode their bicycles for about an hour. The temperature was quite high and prespiration was profuse. The water used in bathing and in extracting the flannels was mixed, evaporated to dryness, and tested for boric acid. A very strong reaction for boric acid was obtained, but the amount present was not sufficient to permit its quantitative determination with certainty. In each case 3 grams of boric acid were administered at the beginning of the experiment. It would appear that in the first experiment the time allowed was not sufficient for the elimination of a sufficient amount of boric acid to give a test. In the case of the second and third, where a positive result was obtained, it can not be expected that the result was as high as would have been the case if the subject had been receiving the preservative for a number of days. As is stated above, about eight days are required for the complete elimination of the boric acid, and the amount eliminated in the first twenty-four hours amounts only to from 30 to 60 per cent of the amount administered. Owing to the small amount of preservative employed, the large amount of water necessary to secure it, and the inevitable inaccuracies due to the incomplete extraction, the amount of boric acid indicated by such an experiment must be incomplete. Probably the greater part of the 23 per cent of the boric acid not accounted for in the urine escapes through the pores of the skin. Attempts were also made to determine whether any of the boric acid assumed a volatile state in the system and escaped in the respiration. The well-known tendency of boric acid to pass off in certain cases in boiling water led to the supposition that it might be reduced in the system to a form in which it would be volatilized in the respiration. One of the members of the table, who had been taking 3 grams of borax a day for four days, breathed as continuously as practicable for three hours through a solution of limewater. The limewater was then tested for boric acid with a negative result. Confirmatory tests were made with the same result. Date. TABLE III.-Boric acid ingested and recovered in urine during Series I. Dose. Amount re- Dose. Amount recovered. a About 4 grams given subject outside of Department. TABLE IV.-Boric acid ingested and recovered in urine during Series II. a Determinations not made on account of lack of sample, but the probable amount of boric acid voided has been added in order not to interrupt the continuity of the data. bOne gram given but not included because urine was not sampled. c Figures for the supplementary period (Feb. 16-21) are not included in the total. Date. Dose. TABLE V.-Boric acid ingested and recovered in urine during Series III. TABLE VI.-Borax ingested and recovered in urine during Series IV. a Determinations not made on account of lack of sample, but the probable amount of boric acid voided has been added in order not to interrupt the continuity of the data. covered. 1 Amount re- Dose. Amount recovered. |