832 
DE. SMITH ON THE ELIMINATION 
18. The rate of excretion of urea to each lb. of body-weight varied only from 4-39 to 
4-74 grs., and rvas 59 per cent, greater than in myself. 
1 9. [The labour of cocoa-matting weaving, as compared with that of tailors, caused the 
weavers to consume more bread, milk, and water; to lose weight; to emit more urine, 
urea, chloride of sodium, and fseces, and consequently more nitrogen ; to exhibit much 
less diminution in the amount of urea evolved on the Sunday, and a little less urea to 
body-weight.] 
20. The elimination of urea was always increased after additional and unusual food, 
as at dinner and evening parties ; and the increase sometimes continued for some days. 
The addition of extra fat to the dietary of the prisoners did not vary the amount of 
urea or urine. Tea, coffee, and alcohol largely decreased the urea on the first and second 
day, but not on the third day. Tea and coffee did not vary the amount of urine ; but 
alcohol lessened it nearly 20 oz. per day. 
21. Chloride of sodium was largely eliminated under the inffuence of tea, and as 
largely retained under that of alcohol ; and in the latter it corresponded with the reduc- 
tion of the urine, viz. 2 7 ’5 and 28-7 per cent. When f oz. of salt was withdrawn from 
the dietary, there was that precise amount deficient in the urine. 
22. With headache and stomach-derangement there was commonly lessened excretion 
of lU’ea, followed by increased excretion on recovery. 
23. Urea and carbonic acid accumulate in the system; and the period of production 
is not that of elimination. Food first causes increased elimination of the stored-up ex- 
cretion, and then supplies material to be transformed. 
The hourly rate of excretion of both is very similar Avith food ; but there is no increase 
of urea after early dinner. The effect of season, temperature, and pressure of the atmo- 
sphere is reversed if the total daily emission of urea may be compared Avith the hasal 
quantities of carbonic acid. 
24. The direct relation of urea is with food, and, under certain conditions, Auries pre- 
cisely as the food if the tissue-weight remains unchanged ; but when the latter varies, 
the relation of urea to food will vary in the same proportion. 
25. Exertion cannot cause increase of urea over the corresponding quantities of nitrogen 
contained in the food, unless the muscular bulk be lessened. Commonly the reparation 
and the waste proceed ;pari ymssu, or the reparation is in excess during the periods of 
rest, and restores the equilibrium on a long average. When there is deficient muscle- 
bulk, increase of food does not induce a corresponding increase in the urea, but a part is 
retained by the muscle. 
The folloAving are the points to which I desire more particularly to direct attention : — 
1. That every question connected with urea is one of great complexity. 
2. That observations made at different hours of the day, and in different seasons of 
the year, cannot be truthfully compared. 
3. That no inquiry less than that involved in the collection of the whole urine evoHed 
in the day can determine the total daily elimination of urea. 
