SODIUM CHLORIDE. 47 



phosphates, taken together, is accordingly about 1 gramme per da}^ ; 

 the magnesian salt being rather the more abundant of the two. 



Both the magnesium phosphate and carbonate, of which latter salt 

 traces occur in the blood, appear to have similar physiological relations 

 with the corresponding salts of lime, and almost the same things may be 

 said in regard to their union with the substance of the more solid tissues 

 and their mode of solubility in the animal fluids. 



5, Sodium Chloride, NaCl. 



This is undoubtedly the most important of the mineral constituents 

 of the body, so far as regards its general distribution and the active part 

 which it takes in the internal phenomena of nutrition. It is the most 

 abundant of all, next to the lime phosphate, and it is universally pre- 

 sent in all the animal tissues and fluids. Its entire quantity in the 

 human body is estimated by Dr. Lankester at 110 grammes, or nearly 

 one-quarter of a pound avoirdupois. In the blood it is rather more 

 abundant than all the other mineral ingredients taken together. Its 

 proportion in the various parts of the body is as follows : 



QUANTITY OF SODIUM CHLORIDE IN 1000 PARTS IN THE 



Bones .... 7.02 Saliva .... 1.53 



Blood .... 3.36 Milk .... 0.30 



Bile .... 3.18 Lymph .... 5.00 



Gastric juice . . . 1.70 Sebaceous matter . * . 5.00 



Perspiration . . . 2.23 Urine .... 5.50 



One of the most important characters of this suit in the living body 

 is undoubted!}' its property of regulating the phenomena of endosmosis 

 and exosmosis, or the transudation of nutritive fluids through the organic 

 membranes. This property is shared more or less by the other mineral 

 ingredients of the blood, but is more important in the case of sodium 

 chloride, owing to its preponderance in quantity as compared with the rest. 



Since this substance is present in all parts of the body, it is also an 

 important ingredient of the food. It occurs, of course, in all animal 

 food, as a natural ingredient of the corresponding tissues. In muscular 

 flesh, however, it is very much less abundant than potassium chloride, 

 while, on the other hand, it is more abundant in the blood. It is present 

 also in various articles of vegetable food. 



According to Boussingault, it exists in the following proportions in 

 certain vegetable substances: 



PROPORTION OF SODIUM CHLORIDE IN 1000 PARTS IN 



Potatoes . . . 0.43 Oats .... 0.11 



Beets .... 0.66 Peas .... 0.09 



Turnips .... 0.28 Beans .... 0.06 



Cabbage . . . 0.40 Meadow hay . . . 3.28 



The relative quantity of sodium chloride taken in animal and vegetable 

 food has not been determined. In regard to the demand for this salt, 



