VARIATIONS IN THE ACIDITY OF THE URINE. 243 
tables, and show in grain-measures the hourly rate of flow 
of the urine. From this volume-measure and the density 
the weight of urine per hour cau be readily calculated. 
III. The Density. A gravimeter of tried accuracy was 
usually employed. When the quantity was too scanty for 
the instrument, a 250-grain specific gravity bottle was 
substituted; and in one set of experiments of seven days 
(Table III.) the bottle was exclusively used. 
IV. The Solid Matters. The amount of solid residue 
per 1000 grains was calculated according to Christison’s 
formula.* A second calculation from this and the hourly 
quantity gave, in grains, the solids separated per hour. 
These are arranged in the fourth columns. It is not pre- 
tended that these figures represent with accuracy the 
actual amounts, but as relative values they may be fairly 
assumed as near the truth. The results obtained are ex- 
ceedingly uniform, considering the somewhat complicated, 
and avowedly uncertain, calculation on which they are 
based; and the remarkable conclusion to which they point 
is indicated with great distinctness. 
V. The Reaction. The degree of acidity or alkalinity 
was ascertained by a test solution after the usual method 
in volumetrical analyses. For the former a solution of 
caustic soda was employed, and for the latter dilute sul- 
phuric acid. The two solutions were made of equal satu- 
rating power; cach 100 grain measures being equivalent 
to 1 grain of dried carbonate of soda. The results are 
arranged in double columns, showing separately, in grains 
of dried carbonate of soda, the degree of acidity or alka- 
lescence per 1000 grain-measures, and the amounts per 
hour. 500 grains of urine were usually operated upon; 
but if the urine was very dilute 1000 grains; and if very 
concentrated and scanty 250 grains were employed. 
VI. The Appearance of the Urine. The condition of the 
* See table in Bird’s Urinary Deposits, 5th edition, p. 60. 
VOL. XV. KK 
