SODIUM CHLORIDE 197 



It forms crystals, which vary in size according to the 

 rapidity of their formation. When pure, it occurs in small, 

 white, crystalline grains, or transparent cubical crystals free 

 from moisture, and has a purely saline taste. From the 

 presence of magnesium and calcium chlorides, many samples 

 are deliquescent. It is soluble in about two and three- 

 quarter parts of water, and insoluble in alcohol. 



ACTIONS AND USES. Salt is an essential article of food ; 

 small doses are restorative, stomachic, and antiseptic ; larger 

 doses are irritant, cathartic, and emetic ; it is used externally 

 as a stimulant, antiseptic, and refrigerant. 



GENERAL ACTIONS. So essential is the regular or frequent 

 use of salt for the maintenance of health, that animals, 

 especially vegetable feeders, in a state of nature instinctively 

 travel many miles to saline springs, the sea-shore, or incrus- 

 tations or beds of salt. Boussingault, experimenting on 

 its dietetic value, selected six cattle, as equal as possible in 

 weight and appearance, and fed them in exactly the same 

 manner, except that three received each 1'2 ounces of salt 

 daily, whilst the other three got none. In about six months 

 the skin and hair of those without salt became rough, dry, 

 and staring, presenting a striking contrast to the smooth, 

 shining coats of the others, which, although little heavier 

 than their neighbours, were more lively, and of so much 

 better appearance that they brought a somewhat higher 

 price. The cattle receiving salt exhibited throughout greater 

 appetite and relish for their food, consumed it in a shorter 

 time, and also drank larger quantities of water. 



A piece of rock salt should constantly He in the horse's 

 manger, the ox's crib, and the sheep's trough. It is specially 

 necessary when the diet consists largely of cooked grains or 

 roots, in the preparation of which part of the salt is apt to 

 be dissolved out. The condiment not only gratifies the 

 palate, but also, as indicated, serves important nutritive 

 purposes. It increases secretion of saliva and gastric juice, 

 furnishes hydrochloric acid for the gastric juice, and soda 

 salts for the bile ; alters the rate of diffusion of fluids through 

 membranes, while four to six parts per 1000 are present in 

 the blood serum, contributing to the solution of the globulins. 

 During convalescence from acute disease the chloride and 



