44 Dr. Parkes on the Elimination of Nitrogen, [June 20, 



Daily Mean Chemical Intensity. 



1866. Kew. Para. Eatio. 



April 6 28-6 242 8'46 



„ 7 77 3010 39-09 



„ 9 5-9 326-4 55-25 



„ 11 25-4 233-2 9-18 



„ 20 38-9 385 9-90 



24 83-6 362-7 434 



The measurements were made at Para in the middle of the rainy sea- 

 son, and at very frequent intervals during the day ; the curves show the 

 enormous and rapid variation in intensity from hour to hour which the 

 chemically active rays undergo under a tropical sun during the rainy 

 season. 



IX. On the Elimination of Nitrogen during Rest and Exercise on 

 a regulated Diet of Nitrogen.'^ By E. A. Parkes, M.D., P.R.S. 

 Received June 1, 1867. 



, The experiments recorded in this paper are intended to complete the 

 inquiry into the effect of rest and exercise on the elimination of nitrogen 

 recorded in the Proceedings of the Eoyal Society (No. 89, 1867). 



The experiments were made on two soldiers at the Eoyal Victoria 

 Hospital at Netley. One of them (S.) was the subject of the former 

 experiments, the other man (B.) was a fresh man. B. is a perfectly 

 healthy temperate man, aged 22^ years, 5 feet 9^ inches in height, and 

 weighing 140 lbs. 



Extreme care was taken to ensure the greatest accuracy both as to 

 food and as to the collection of the excreta. The whole value of such 

 experiments as these, depends on the exactness with which all the con- 

 ditions are carried out ; and without perfect accuracy, the results would 

 only mislead. I have every confidence that the conditions were faith- 

 fully observed ; there is in fact evidence of this from the experiments 

 themselves. 



The course of the experiments was precisely the same as in the obser- 

 vations recorded in the last paper, except that the diet was during sixteen 

 days exactly the same on each day. During four days the men were at 

 their ordinary employment; during two days rested; returned to ordinary 

 work for four days; took very active exercise for two days ; and were then 

 for four days more on ordinary occupation. 



They took each day the same amount of food, viz. : — 



