573 



tint must be multiplied by the following factors to determine the 

 amount of urea per ounce : 



With equal parts of each multiply by 8 



"With 2 parts of urine and 1 part of solution of baryta 1 



multiply by J 



With 3 parts of urine and 1 part of solution of baryta T 



multiply by J 



With 4 parts of urine and 1 part of solution of baryta 1 



multiply by J 



Considerable and constant practice is essential to correct and com- 

 parable results. 



The periods of the formation and the elimination of urea are dif- 

 ferent, and there is no known method of showing the former. The 

 urea from metamorphosis of tissue and from the transformation of 

 food is a mixed and varying product, and the two sources cannot be 

 dissociated. The direct relation of urea is with food, since, in the 

 absence of exertion, it nearly represents the nitrogen in the food 

 supplied, less that remaining in the faeces. The elimination of 

 urea chiefly varies with the quantity of urine, and therefore will be 

 influenced by the same agencies as affect the discharge of urine. 

 Hence the duration of inquiries to determine the normal daily rate 

 of elimination at distant periods of the year, must be the same as 

 that indicated in reference to the urine. There are great and frequent 

 variations in the daily elimination of urea in a person of the most 

 regular habits ; and as the effect of any agent is often carried on to 

 the following day, inquiries which may be made for a short period 

 before breakfast will not faithfully represent the conditions of that 

 day. 



WEIGHT OF BODY*. 



The only satisfactory method of determining the weight of a person 

 day by day, is to weigh him naked directly after he has passed urine 

 and before he has taken^any_ingesta, and to do so as nearly as possible 

 at the same hour every morning. The error which will be due to 

 the varying amount of faeces contained in the bowel will still exist, but 

 it cannot be large, and by no method can it be entirely removed. 

 The person cannot weigh himself unless stand-scales with a multi- 

 * See Phil. Trans. 1861. 



