URINE AND ITS SPECIFIC GRAVITY. 



573 



other case, upon a diet of bread with a little butter, again with water 

 as a beverage : 



These analyses are interesting as showing the effect of two widely 

 differing forms of diet ; but they must not be taken as typical of the 

 relative effect of animal and vegetable diet in any absolute sense. As 

 regards such factors, for instance, as the relative proportion between 

 urea and uric acid, we shall find that, even when one or other of the 

 two types of diet (animal or vegetable) is adhered to, great differences 

 may be seen as the effect of variation in the specific composition of 

 either. Indeed, no great importance must be attached to the details of 

 collective quantitative analyses of the urine, except where the diet itself 

 has been simultaneously analysed. While abundant observations of this 

 kind have been published, relating to particular constituents of the 

 urine, no collective analyses appear to have been made upon the same 

 specimen of urine after a diet of known quantity and composition. 



The following figures, which give the mean of many determinations 

 made by Yvon and Berlioz, show the differences in the excretion of 

 certain constituents by males and females respectively : 



THE QUANTITY OF URINE AND ITS SPECIFIC GRAVITY. 



A human adult excretes from 1200 to 1700 c.c. of urine in the 

 twenty -four hours, or about 1 c.c. per kilo, of body weight per hour. 

 During sleep the amount is less than at other times. The specific 

 gravity commonly varies from 1015 to 1025, and is, in general, inversely 

 as the quantity excreted. 



