70 PROXIMATE PRINCIPLES OF THE FIRST CLASS. 



by giving them the special consistency which is characteristic of 

 them, and which would be lost without it. Thus a tendon, in its 

 natural condition, is white, glistening, and opaque ; and though very 

 strong, perfectly flexible. If its water be expelled by evaporation 

 it becomes yellowish in color, shrivelled, semi-transparent, inflexi- 

 ble,, and totally unfit for performing its mechanical functions. The 

 same thing is true of the skin, muscles, cartilages, &c. 



The following is a list, compiled by Eobin and Verdeil from 

 various observers, showing the proportion of water per thousand 

 parts, in different solids and fluids : 



QUANTITY OF WATER IN 1,000 PARTS IN 



Epidermis ... 37 Bile 880 



Teeth . . . .100 Milk . . . .887 



Bones .... 130 Pancreatic juice . . 900 



Cartilage . . . .550 Urine . . . .936 



Muscles . . . .750 Lymph . . . .960 



Ligaments . . . 768 Gastric juice . . . 975 



Brain .... 789 Perspiration . . . 986 



Blood . . . .795 Saliva . . . .995 

 Synovial fluid . . . 805 



According to the best calculations, water constitutes, in the 

 human subject, between two-thirds and three-quarters of the entire 

 weight of the body. 



The water which thus forms a part of the animal frame is derived 

 from without. It is taken in the different kinds of drink, and also 

 forms an abundant ingredient in the various articles of food. For 

 no articles of food are taken in an absolutely dry state, but all 

 contain a larger or smaller quantity of water, which may readily 

 be expelled by evaporation. The quantity of water, therefore, 

 which is daily taken into the system, cannot be ascertained in any 

 case by simply measuring the quantity of drink, but its proportion 

 in the solid food, taken at the same time, must also be determined 

 by experiment, and this ascertained quantity added to that which 

 is taken in with the fluids. By measuring the quantity of fluid 

 taken with the drink, and calculating in addition the proportion 

 existing in the solid food, we have found that, for a healthy adult 

 man, the ordinary quantity of water introduced per day, is a little 

 over 4 \ pounds. 



After forming part of the animal solids and fluids, and taking 

 part in the various physical and chemical processes of the body, the 

 water is again discharged; for its presence in the body, like that 

 of all the other proximate principles, is not permanent, but only 



