INORGANIC ALIMENTARY PRINCIPLES. 65 



The quantity, however, which is taken in combination with 

 other principles is usually insufficient for the purposes of 

 the economy, and common salt is generally added to certain 

 articles of food as a condiment, when it improves their flavor, 

 promotes the secretion of some of the digestive fluids, and 

 meets a positive nutritive demand on the part of the system. 

 Numerous experiments and observations have shown that a 

 deficiency of chloride of sodium in the food has an unfavor- 

 able influence on nutrition. 1 



Phosphate of Lime. This is almost as common a con- 

 stituent of vegetable and animal food as the chloride of sodi- 

 um. It is seldom taken except in combination, particularly 

 with the nitrogenized alimentary principles. Its importance 

 as an alimentary principle has been experimentally demon- 

 strated, it having been shown that in animals deprived as 

 completely as possible of this substance, the nutrition of the 

 body, particularly in parts which contain it in considerable 

 quantity, as the bones, is seriously affected. 2 



Iron. Hsematine, the coloring matter of the blood, con- 

 tains, intimately united with organic matter, a considerable 

 proportion of iron. The examples of anaemia which are 

 daily met with in practice, and are almost always relieved in 

 a short time by the administration of iron, are proof of the 

 importance of this substance as an alimentary principle. 

 The quantity of iron which is discharged from the body is 



1 See vol. i., Introduction. 



2 Chossat fed pigeons for a length of time exclusively on wheat which had 

 been carefully cleaned so as to remove every particle of calcareous matter. He 

 found that this diet answered very well for three months ; but after that time 

 diarrhoea set in, and the animals died between the eighth and the tenth month. 

 One of the most remarkable points in these experiments related to the condition 

 of the bones, which became excessively thin and fragile. One animal^was found 

 with both femurs and tibias fractured ; and examined after death, it was found 

 that the bony tissue had disappeared from many parts of the sternum. None of 

 these effects were observed when a little carbonate of lime was added to the food. 

 (Comptes Rendus, Paris, 1842, tome xiv., p. 452.) 



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