ITS CHEMICAL CONSTITUENTS. 17 



that of bones in general, that the most essential organic consti- 

 tuents are gelatigenous cartilage (vol. i, p. 396) and fat (vol. i, 

 p. 249), while the inorganic are phosphate of lime (vol. i, p. 412), 

 phosphate of magnesia (vol. i, p. 422), carbonate of lime (vol. i, 

 p. 418) and fluoride of calcium (vol. i, p. 424). In addition to these 

 main constituents, the bones also contain substances which must be 

 regarded as incidental or unessential constituents of osseous sub- 

 stance. Thus the alkaline sulphate in Bibra's cases* (see vol. i, 

 p. 444) should probably be regarded as for the most part the pro- 

 duct of the incineration of the bones. With regard to the other 

 soluble salts that can be extracted by water or spirit from fresh 

 pulverized bones after the removal of their fat, we possess no 

 investigations which enable us to decide the question whether the 

 chloride of sodium, carbonate of soda, &c., are at all events in part 

 peculiar to the matrix of bone, or whether they only belong to the 

 blood which can never be thoroughly removed, or to the fluid con- 

 tents of the bone- corpuscles and their prolongations. Precisely 

 the same may be said of the organic substances which may be 

 extracted from pulverized bone by digestion with mere water, or 

 more thoroughly (together with the earthy salts) by dilute hydro- 

 chloric acid. Even the fat which we have enumerated amongst 

 the main constituents can only occur in extremely small quantity 

 in the matrix of bone. For the small quantity of fat (from 1 to 

 3) which we find in bones that have been as thoroughly as pos- 

 sible cleaned and macerated, must be chiefly marrow from the 

 cavities of the spongy portions of the bones, and only a mere trace 

 can arise from the matrix: we, moreover, find from the investigations 

 of the most distinguished histologists, that the marrow does not pass 

 into the Haversian canals of the compact osseous substance. Hence 

 it is only by the analyses of bones which have been well macerated 

 and deprived of their fat that we can hope to arrive at any definite 

 conclusion regarding the constitution of the osseous matrix. 



The bone-cartilage, obtained by prolonged digestion with dilute 

 and frequently changed hydrochloric or nitric acid, occurs in its 

 moist state as a tolerably elastic, yellowish, translucent substance, 

 which perfectly retains the form of the portion of bone from which 

 it was obtained. When dried, it becomes very hard, but only 

 slightly brittle. When it has been so often extracted with a weak 

 acid solution that the latter no longer exhibits any traces of dis- 

 solved lime, the cartilage leaves very little or a mere trace of ash on 

 incineration. We have already mentioned that neither Marchand 

 * [See the foot-note in page 21.] 



VOL. III. C 



