436 NUTRITION ANIMAL HEAT AND FORCE. 



alkaline without being ammoniacal ; in the urine of the herbivora ; and in 

 the lymph, cephalo-rachidian fluid and bone. The analyses by different 

 chemists, with regard to this substance, are very contradictory, on account of 

 its formation during the process of incineration ; but there is no doubt that 

 it is found in the above situations. The following table gives the quanti- 

 ties which have been found in some of the fluids and solids : 



TABLE OF QUANTITIES OF SODIUM CAKBOSTATE. 



Parts per 1,000. 



In blood of the ox (Marcet) 1-62 



In lymph (Nasse) 0-56 



In cephalo-rachidian fluid (Lassaigne) 0-60 



In compact tissue of the tibia in a male of 38 years (Valentin) 2'00 



In spongy tissue of the same (Valentin) 0*70 



Uses of Sodium Carbonate. This substance has a tendency to maintain 

 the fluidity of the albuminoid constituents of the blood, and it assists in pre- 

 serving the form and consistence of the blood-corpuscles. Its office in nutri- 

 tion is rather accessory, like that of sodium chloride, than essential, like cal- 

 cium phosphate, in the constitution of certain structures. 



Origin and Discharge of Sodium Carbonate. This substance is not intro- 

 duced into the body as sodium carbonate, but it is formed, as is calcium 

 carbonate in part, by a decomposition of the malates, tartrates etc., which 

 exist in fruits. It is discharged occasionally in the urine of the human sub- 

 ject, and a great part of it is decomposed in the lungs, carbon dioxide being 

 set free, which latter is discharged in the expired air. 



Potassium Carbonate. This salt exists particularly in herbivorous ani- 

 mals. It is found in the human subject under a vegetable diet. Under the 

 heads of uses, origin and discharge, what has been said with regard to sodium 

 carbonate will apply to potassium carbonate. 



Magnesium Carbonate and Sodium Bicarbonate. It is most convenient 

 to take up these two salts in connection with the other carbonates, though 

 they are among the least important of the inorganic constituents of the 

 body. Traces of magnesium carbonate 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 indicated the presence of sodium bicarbonate in the blood. 

 In this form a certain quantity of carbon dioxide is carried to the lungs, to 

 be exhaled in the expired air. 



Magnesium Phosphate, Sodium Phosphate (neutral) and Potassium 

 Phosphate. These salts are found in all the fluids and solids of the body, 

 though not in a very large proportion as compared with calcium phosphate. 

 In their relations to organized structures, they are analogous to calcium 

 phosphate, 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 are in great part the 

 result of the decomposition by carbon dioxide of the malates, tartrates, oxa- 



