418 FIRST CLASS OF MINERAL CONSTITUENTS. 



amount of ash was diminished almost solely at the expense of the 

 phosphate of lime. In the callus, as well as in the exostosis of a 

 horse, he found the carbonate of lime increased in relation to the 

 phosphate, and hence concluded, that, as a general rule, imperfectly 

 formed bones always contain more carbonate of lime than normal 

 bones. Lassaigne's experiments* accord with those of Valentin. 

 In the osteophyte occurring on the inner layer of the skull during 

 pregnancy, there is also much carbonate of lime, as was observed 

 by Kiihn; I found 52'46-g- of organic matter, 30'69-g- of phosphate 

 of lime, 1'09 of phosphates of magnesia and iron, 98-g- of soluble 

 salts, and 14'78-g- of carbonate of lime in one of these osteophytes. 

 Proutf was the first who observed that during the incubation of 

 the egg the quantity of phosphorus in its contents remains constant, 

 but that the quantity of lime undergoes a considerable augmentation; 

 he was almost inclined from this observation to conclude that there 

 was a formation of lime from other materials, since he did not re- 

 gard it as probable that the non-vascular membrana putaminis could 

 transfer lime from the shell to the embryo. But if we take into con- 

 sideration that during incubation the shell experiences a loss both 

 in weight and firmness, and that a part of this membrana putaminis 

 becomes dried, and consequently impermeable, while, however, 

 the greater part is in contact with the contents and thus remains 

 moist, it is very easy to perceive that the increase in the amount 

 of lime within the egg arises from its most proximate source, 

 namely, from the shell itself. The phosphorus exists chiefly in 

 the yolk, where it occurs as glycero-phosphoric acid, which during 

 incubation is gradually decomposed, so that the liberated phos- 

 phoric acid unites with lime which passes over by endosmosis from 

 the shell into the egg to form this salt. There is, however, so 

 much phosphorus contained in the yolk of the egg, that on inci- 

 neration it forms acid phosphates, or rather metaphosphates 

 (NaO.KO.PO 5 ), with tlie bases which it there encounters. 



CARBONATE OF LIME. 



This salt is principally found in the skeletons of invertebrate 



animals ; but it always occurs, as has been already mentioned, in 



reater or smaller quantities, in the bones of the vertebrata. Its 



uses in the animal organism are the same as those of phosphate 



of lime 



* Journ. de Chim. m^d. T. 4, p. 366. 

 t Phil. Trans. 1822, p. 365. 



