CHLORIDE OF SODIUM. 3 



and act upon the permanganate. This is the case, for instance, 

 with sulphurous acid, which is constantly present in an atmo- 

 spherb vvnere coal and coal gas are burned." 



II. CHLORIDE OF SODIUM. Common salt enters largely 

 into the composition of animals and vegetables; and when 

 absent in the food of the former, a morbid craving for it is 

 frequently observed. Its effects on the system, when directly 

 introduced, are most salutary; and, in some diseases, it is 

 valuable as a preventative and curative. It is composed of 

 two elements possessing powerful chemical affinities. The 

 one is an actively bleaching gas, chlorine; and the other a 

 metal, susceptible of very ready oxydation, sodium. These 

 elements are not separated in the system; and one of the 

 greatest uses they serve in combination is not in connection 

 with chemical changes, but rather with the physical transuda- 

 tion, or endosmosis and exosmosis occurring so constantly in 

 the system. 



The quantity of common salt in different constituents of 

 the body, is stated by Kobin and Verdeil as follows, in 1000 

 parts : 



Muscles . . 2-0 



Bones . . . 2'5 



Milk .... 1-0 

 Saliva. . . .1.5 

 Unne . 3.0 



Bile . . 3-5 



Blood . . . .4.5 

 Mucus 6'0 



Aqueous Humour . 11 -0 

 Vitreous Humour . 14.0 

 The value of common salt, as an article of diet, is proved 

 by experiments, performed by Boussingault, on bullocks. He 

 gave three 500 grains of salt per day, and other three had 

 none. He says : " Though salt, administered with the food, 

 has but little effect in increasing the size of the animal, it 

 appears to exert a favourable influence upon his qualities and 

 general aspects. Until the end of March (the experiment 

 began in October), the two lots experimented on did not 



