114 



ON THE BONES, &c. 



is membrane, with a larger proportion of albumen to give it a still greater degrea 

 of solidity; and bone and shell are mere cartilage, hardened by the insertion 

 of lime into their interior, the lime being secreted for this purpose by a particular 

 set of vessels, and absorbed by the bony or shelly rudiments in their soft state. 

 And hence any substances which, like the mineral acids, for example, have a 

 power of dissolving the earthy matter of the two last, and of leaving the car- 

 tilage untouched, may be readily employed as reagents, to reduce them to 

 their primary softness : and it was by this means that Cleopatra, as we are 

 told by Pliny, dissolved one of the costly pair of pearls that formed her ear- 

 rings, each of which was valued at upwards of eighty thousand pounds [centies 

 sestertium), at a feast given to Mark Antony, and then presented it to him in a 

 goblet, with an equal mixture of wine.* 



In the adult state, however, as well as in the embryo state, it is necessary 

 that the bones, like every other substance of the animal frame, should be 

 punctually supplied with the elementary matter, or the means of forming the 

 elementary matter, of which it essentially consists, the old matter of every 

 kind being worn out by use, and carried away by a distinct set of vessels, 

 called lymphatics or absorbents. It is the office of the digestive organs to 

 receive such supply from without, and to prepare it for the general use. 

 And hence, if we could conceive it possible for these organs, or any organs 

 dependent upon them, to be so peculiarly diseased as to be incapable of pre- 

 paring or conveying to the bones a sufficient quantity of lime (of which some 

 portion is contained in almost every kind of food) to supply the place of that 

 which is perpetually passing off, the necessary consequence would be, that 

 the bones would progressively lose their hardness, and become cartilaginous 

 and pliable. Now we sometimes do meet with the digestive or the secretory 

 organs affected by such a kind of disease, and that both in children and adults. 

 In children it is more common, and is called rickets; in grown persons it is 

 simply called a softness of the bones, or mollities ossium. In the former 

 case, the softened spine becomes bent from the weight of the head, and other 

 extremities, which it is now no longer able to sustain, while the chest and 

 most of the limbs partake of the general distortion. In the latter case many 

 of the bones are sometimes reduced to imperfect cartilages, and can be bent 

 and unbent in any direction. 



Lime, however, is never found in the animal system in its pure state, and 

 is certainly never introduced into it in such a state. It is usually combined 

 with some acid, either the phosphoric, in which case the compound is called 

 phosphate of lime ; or carbonic acid gas, when it is called carbonate of lime, 

 or common chalk. 



It is of no small importance to attend to the nature of these two acids ; for 

 it is the difference between them that chiefly constitutes the difTerence be- 

 tween bones and shells ; bones uniformly consisting of a larger proportion 

 of phosphate of lime, or lime and phosphoric acid, and a less proportion of car- 

 bonate ; and shells of a larger proportion of carbonate of lime, and a less pro- 

 portion of phosphate. There are a few other ingredients that enter into the 

 composition of both these substances, and which are chiefly obtained from 

 the materials of common salt, as sulphuric acid and soda ; but the proportions 

 are too small to render it necessary to dwell upon them in a course of popu- 

 lar study. Bones, shells, cartilages, and membranes may therefore be re- 

 garded as substances of the same kind, differing only in degree of solidity 

 from the different proportions that they possess of albumen and salts 

 of lime. 



Teeth, horn, coral, tortoise-shell, fish-scales, and the crustaceous integu- 

 ments of crabs, millepedes, and beetles, are all compounds of the same ele- 

 ments combined in different proportions, and rendered harder or softer as 

 they possess a larger or smaller quantity of calcareous salts ; ivory and the 



♦This was on a trial who could give the most sumptuous banquet. Munacius Plancus was the arbiter. 

 The expense of Mark Antony's, already bestowed, had been valued at just the price of this single pearl. 

 Cleopatra was proceeding to dissolve its fellow, when she was suddenly stopped by the umpire, who de« 

 clared the victory to be hers. Plin. Hist. Nat. lib. ix. 35. 



