There is no part of the body which does not contain, or does not yield on incineration, phosphate of lime. It gives solidity to the osseous framework of the body, and, when too little is furnished during the growing period, rickets and mollities ossium are the result. The demand made on the system of the mother for the supply of this essential material for the growth of the osseous structure of the foetus is so great that her fractured bones unite with difficulty. The bones of animals, fed on food deficient in phosphate of lime, soften. All the animal fluids contain this substance in solution: thus it is found in the blood, the saliva, the gastric juice, milk, urine, and in the intercellular fluid throughout the body. It accumulates wherever tissue-changes are rapidly taking place (Dusart). It is obviously very important to the nutritive processes of the body.

As phosphate of lime is to a limited extent soluble in lactic and hydrochloric acids, it is evident that, administered by the stomach, diffusion into the blood must occur. Large amounts can not, however, be disposed of in this way; hence small doses must be as effective, in the treatment of the maladies for which it is prescribed, as large ones —for all in excess of the quantity soluble in the free acids of the stomach must pass off with the faeces or form intestinal concretions.