4(5 INOKGANIC PKOXIMATE PRINCIPLES. 



The source of the lime phosphate of the animal solids and fluids is in 

 the food. This substance exists in nearly every animal and vegetable 

 alimentary matter in common use. It is found not only in muscular 

 flesh, eggs, and milk, and in all the cereal grains, as wheat, rye, oats, 

 barley, maize, and rice, but also in peas and beans, the nutritive tubers 

 and roots, as potatoes, beets, turnips, and carrots, and even in the 

 juicy fruits, such as the apple, pear, plum, and cherry. 



After forming for a time a constituent part of the body, the lime 

 phosphate is again discharged with the excretions, but very slowly and 

 in small amount. According to the observations of Neubauer and 

 Beneke about 0.4 gramme, on the average, is daily expelled with the 

 urine. A slightly larger quantity is also found in the feces, but this 

 may be only the residue derived from the undigested portion of the food. 

 Only traces of it are to be detected in the perspiration. As so large a 

 quantity of this salt, therefore, is contained in the body, while so small 

 a proportion is expelled daily with the excretions, it is evidently to be 

 regarded as one of the more permanent constituents of the frame ; being 

 comparatively inactive in the process of internal metamorphosis, and 

 serving for the most part as a physical ingredient of the solid tissues. 



3. Lime Carbonate, CaC0 3 . 



Lime carbonate is to be found in the bones, the teeth, the blood, the 

 lymph and chyle, the saliva, and sometimes in the urine. In all these 

 situations it is normally in much smaller proportion than the calcareous 

 phosphate with which it is associated. In the bones, however, it is next 

 in importance to the lime phosphate, being on the average one-seventh 

 as abundant as that salt, and much more so than any of the remaining 

 mineral ingredients. In the animal fluids its solubility is accounted for 

 by the presence of the alkaline chlorides or by that of free carbonic acid. 



4. Magnesium Phosphate, MgHP0 4 . 



Magnesium phosphate was formerly associated with the corresponding 

 lime salt under the name of the earthy phosphates, owing to certain 

 resemblances in their chemical relations. Like the lime phosphate, which 

 it everywhere accompanies, it is present in all the tissues and fluids of 

 the body, though this substance is for the most part in the smaller 

 quantity of the two. Thus in the bones the lime phosphate is in the 

 proportion of 516 parts per thousand, while the magnesium phosphate 

 forms only 12.5 parts. In the blood the calcareous salt amounts to 0.30 

 part per thousand, the magnesium salt to 0.22 part ; and in the milk 

 there are 2.72 parts of lime phosphate to 0.53 part of magnesium phos- 

 phate. On the other hand, the salts of magnesium have been found to 

 be in larger quantity than those of lime in the muscles, and nearly twice 

 as abundant in the substance of the brain. 



The magnesium phosphate is discharged, by the urine, in the average 

 daily quantity of 0.6 gramme. The average amount of both the earthy 



