774 
I>E. SMITH ON THE ELIMINATION 
There was thus a progressive decrease in the amount of urea found in each ounce of 
urine as the quantity of the latter evolved daily increased ; but the quantity of urea in 
the lowest was proportionately greater than in the higher decades, and the decrease was 
more rapid in the ascent from the two lowest decades. If the decade between 50 and 
60 fluid ounces be accepted as the central point of this variation, it will be obser\’ed 
that the degree of divergence differs greatly at the two extremes, although equidistant ; 
so that it is the greatest in the upper and the least in the lower decades. In reference 
to the total daily quantity of iwea evolved, the difference was an increase of 16|- per 
cent, with the highest, and a decrease of 9’6 per cent, with the lowest decades ; but in 
reference to the quantity of urea in each ounce, the increase with the lowest decade 
was 100 per cent., whilst the decrease with the highest decade was only 24 per cent. 
Thus with increase of urinary water there was a greater increase in the urea than there 
was a decrease of urea with decrease of urinary water, and the least difierence in the 
amount of urea in each ounce of urine. The average proportion of urea and urinary 
water throughout the year was 9 ’77 grains of the former in each fluid ounce of the latter ; 
and assuming the average specific gravity of the urine to be 1020, the proportion of urea 
to urinary water was 2T9 per cent. 
4. Period of the day. 
Pakkes states that the quantities of the ingredients of the urine are the highest in the 
afternoon and evening, from the effect of the dinner and the exertion of the day. 
Dkapee found the quantity of urea to have lessened in the night, but the urinary water 
was equal in the day and night. Kaupp found that when there was a large excretion 
in one period there was a small one in the other ; and Paekes noticed a certain oscilla- 
tion extending to two or three days. Eaupp also ascertained that there was a diminu- 
tion in the excretion of urine, urea, and chloride of sodium during the night. In none 
of these inquiries were the hours of the day and night defined, neither were the condi- 
tions as to the ingesta and the hours of the meals alike. 
In stating the results of my own inquu'ies, I shall arrange them under two heads, viz. 
with ordinaiy food, and with fasting or variation from ordinaiy food. 
A. With ordinary food. 
This part of the inquiry has been investigated by several series of experiments. The 
amount of urea and urinary water evolved per hour was determined thrice a day through- 
out nearly the whole year, viz. the average excretion of the whole day, the average of 
the night, and the quantity secreted in the morning, after the night urine had been 
voided, and before any fluid or solid food had been taken. The two former embraced 
lengthened periods, whilst the latter extended to from twenty minutes to one hour only. 
The object in determining the latter quantity was to ascertain if, at the period of the 
day when the system was the least influenced by food, there was so uniform a produc- 
tion of urea as to constitute a standard with which to compare the quantities produced 
