INORGANIC PRINCIPLES. 497 



lungs by the action of pneumic acid, setting free carbonic acid, which is discharged in 

 the expired air. 



Carbonate of Potassa. This salt exists particularly in herbivorous animals. It is 

 found in the human subject when subjected to a vegetable diet. Under the heads of func- 

 tion, origin, and discharge, what has been said with regard to the carbonate of soda will 

 apply to the carbonate of potassa. 



Carbonate of Magnesia and Bicarbonate of Soda. It is most convenient to take up 

 these two salts in connection with the other carbonates, though they are put at the end 

 of the list of inorganic substances as the least important. "We know very little about 

 them, chemically or physiologically. Traces of carbonate of magnesia have been found 

 in the blood of man, and it exists normally in considerable quantity in the urine of 

 herbivora. In the human subject it is discharged in the sebaceous matter. 



Liebig has merely indicated the presence of bicarbonate of soda in the blood. 



Phosphate of Magnesia, Phosphate of Soda (neutral), and Phosphate of Potassa. These 

 salts are found in all the fluids and solidg of the body, though not existing in a very large 

 proportion, as compared with the phosphate of lime, which we have already considered. 

 In their relations to organized structures, they are analogous to the phosphate of lime, 

 entering into the composition of the tissues, and existing there in a state of intimate 

 combination. They are all taken into the body with food, especially by the carnivora, in 

 the fluids of which they are found in much greater abundance than the carbonates ; 

 which latter, as we have already seen, are in great part the result of the decomposition 

 by carbonic acid of the malates, tartrates, oxalates, etc. With respect to their functions, 

 we can only say that, with the phosphate of lime, they go to form the organized struct- 

 ures of which they are necessary constituents. They are discharged from the body in 

 the urine and faeces. 



Sulphate of Soda, Sulphate of Potassa, and Sulphate of Lime. The sulphate of soda 

 and the sulphate of potassa are identical in their situation, and apparently in their func- 

 tions. They are found in all the fluids and solids of the body, except in the milk, bile, and 

 gastric juice. Their origin in the body is from the food, in which they are contained in 

 small quantity, and they are discharged in the urine. Their chief function appears to be 

 in the blood, where they tend to preserve the fluidity of the albuminoid matters and the 

 form and consistence of the blood-corpuscles. The sulphate of lime is found in the blood 

 and faeces. It is introduced into the body in solution in the water which is used as drink, 

 and it is discharged in the faeces. Its function is not understood and is probably not very 

 important. 



Hydrochlorate of Ammonia. This substance has simply been indicated by chemists 

 as existing in the gastric juice of ruminants, the saliva, tears, and urine. Some chemists 

 make a rearrangement of its atoms, calling it chloride of ammonium. It is discharged in 

 the urine, in which it exists, according to Simon, in the proportion of 0'41 part per 1,000. 

 Its origin and function are unknown. Various combinations of bases with organic acids 

 taken as food, as the acetates, tartrates, etc., found in fruits, undergo decomposition in 

 the body and are transformed into carbonates. In this form they behave precisely like 

 the other inorganic salts. 



Principles consumed by the Organism. 



All of the assimilable organic matter taken as food is consumed in the organism, and 

 none is ever discharged from the body, in health, in the form under which it was intro- 

 duced. The principles thus consumed in nutrition have been divided into nitrogenized 

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