

BORIC ACID AND BORAX. 167 



The apparatus in which these determinations were made consists of a 

 tin box through which tubes of hard glass are passed. The box is filled 

 with sand and kept at a temperature of 95 to 100, the inside temper- 

 ature of the tubes being from 90 to 95. The air is first led through 

 concentrated sulphuric acid, then through a tube of soda lime and cal- 

 cium chlorid, and finally preheated by passing through hard glass tubes 

 heated by means of a Bunsen burner. Small glass boats which readily 

 hold 5 cc of urine are employed for the drying. The solid residue is 

 obtained in about two and one-half to three hours and kept in a desic- 

 cator for three hours before weighing. The determinations agreed 

 closely throughout, particularly in the case of individuals, and an 

 average of a number of determinations gave the figure 0.245, which was 

 adopted and used in the calculation of the solids throughout the work. 

 In the application of this factor the last three figures of the specific 

 gravity are multiplied by 0.245 which gives the amount of total solids 

 in one thousand parts of the sample. The calculation is then made for 

 the given volume. In making these calculations a "slide rule" was 

 used, and therefore the results are not exactly accurate in the third 

 decimal place. 



SERIES I. 



In the fore period of Series I the highest average specific gravitv for 

 any one person is found in the case of No. 1, namely, 1.0282, and this 

 corresponds with next to the largest quantity of total solids eliminated, 

 namely, 61.563 grams. In the case of No. 2, while the specific gravity 

 is somewhat lower, the average quantity of urine excreted is higher, 

 and the total solid matter, 63.721 grams, excreted daily, is somewhat 

 higher than in the case of No. 1. The most notable departure in 

 specific gravity from the average is found in the cases of Nos. 4 and 5, 

 where the density of the urine is considerably lower than in the other 

 cases. This, however, is partly at least accounted for by the greater 

 volume of urine voided by these two subjects. The average specific 

 gravity of the fore period for the six men is 1.0251, and the average 

 quantity of total solids eliminated per day is 57.431 grams. 



As would naturally be supposed in cases of health and a normal 

 exercise of the functions of the kidneys, the density of the urine 

 would be inversely as the quantity. The total solid matter excreted 

 in the urine would also depend largely on the degree of metabolic 

 activity as conditioned by $xercise, quantity of food, and external 

 temperature. The greater the amount of exercise the more tissue 

 broken down, and hence the greater tendency to excrete solid matter 

 in the urine. The lower the temperature, on the other hand, the 

 greater the tendency to increase the volume of urine, thus diminishing 

 its specific gravity, but not necessarily altering the quantity of solid 

 matter voided. 



