PHOSPHATE OF LIME. 413 



unite at all. Chossat* was able to induce softening of the bones 

 artificially in animals, when he restricted them to food containing 

 little or no phosphate of lime. The permanent cartilages only 

 ossify in old age, when a superabundance of calcareous salts is 

 deposited in them. In the dense, cortical portion of bones, we 

 find more bone-earth deposited than in the spongy parts. The 

 teeth, whose utility depends entirely on their hardness, contain a 

 larger proportion of phosphate of lime than any other part of the 

 animal body; and it exists in still greater quantity in the enamel 

 than in the dentine. 



We have previously had occasion to remark that Berzelius, even 

 to a recent time, adhered to the formula 8CaO.3PO 5 for the phos- 

 phate of lime of bone-earth, and that on the other hand the inves- 

 tigations of W. Heintz under Rose's direction, indicate that the 

 formula for the composition of bone-earth should be 3CaO.PO 5 . 

 Berzeliusf has in part given the reason for his formula. It is not 

 always 8CaO.3PO 5 which is precipitated from acid solutions con- 

 taining lime and phosphoric acid, as he formerly assumed ; but 

 when there is an excess of lime, and under the prolonged action of 

 caustic ammonia, the basic salt 3CaO.PO 5 is precipitated. Since 

 the phosphate of lime is for the most part separated in this way, 

 and the lime which is precipitated after the removal of the phos- 

 phate is calculated as if it were a carbonate, without any direct 

 determination of the carbonic acid, there must be some uncertainty 

 in the ordinary analyses of the earthy constituents of the bones, in 

 part owing to the not very accurate determination of the magnesia. 

 Heintz has found that this is the composition of phosphate of lime 

 not only in normal human bones, but also in those of the sheep and 

 the ox. In this point of view, however, the investigation of 

 diseased bones requires a thorough revision ; moreover, von 

 Bibra'sJ analyses seem to show that in the teeth the ratio of the 

 phosphoric acid to the lime is not in accordance with either of the 

 above formulae. 



In healthy human bones the phosphate of liaie ranges from 

 48 to 59; in softening of the bones it may sink to 30%. It is, 

 however, singular that in almost all diseases of the bones, whether 

 the results of osteoporosis, osteomalacia, or osteopsathyrosis, we 

 find a diminution of the phosphate of lime. Even in consecutive 



* Gaz. ni(M. 1842, p. 208. 



t Ann. d Ch. u. Pharm. Bd. 53, S. 280-289. 



+ Chem. Unters. iib. Knocken u. Zaline. Schweinfurt, 1844, S. 284-287. 



