BON f I5S ) BON

becomes foft, flexible, and porous, but retainingits original fhape. The acid at the fame timeflowly dilfolves out the gelatin (becoming there-by fomewhat vifcid and yellow) and alfo all theearthy part, fo that at laft nothing is left butan open reticulated cartilage or fpongy cellularmembrane. If the bone has been previouflyboiled the experiment will fucceed as well, onlythere will remain lefs gelatin for the acid todiflolve, being already chiefly extracted by thewater.

This fpongy cartilage is effential to the con-ftitution of all organized bones, and alfo of allfhells and other hard coverings of animals, andit is the part firft formed by nature, being as itwere the outline or fketch of the bone, whichafterwards receives folidity and ftrength by thegradual depolition of the earthy part. Thisrudimental cartilage is molt confpicuous in thefoetal Hate and in animals juft born, whofebones are yet foft and flexible, but graduallyacquire hardnefs and denfity by the increafe ofthe earthy part in the procefs of oflification.Bony cartilage being infoluble both in waterand in weak acids is therefore feparable from thegelatin by the former menftruum, and from theearthy parts by the latter, but it cannot bereadily exhibited in any other way than thatabove mentioned. Mr. Hatchett has found itto refemble coagulated albumen , and to differfrom gelatin by the following decifive marks.

When dry it is femitranfparent like horn andmore or lefs brittle. In this ftate it fo muchrefills the a£tion of water that it may be boiledwith this fluid for many days without fenfiblydiminilhing; whereas the gelatin even of thehardeft bones, as we have feen, is readily ex-trafted by this fluid. The high heat of Papin’sdigefter will however enable water to diffolveeven coagulated albumen.

It is fcarcely a£!ed on by any acid if dilute,and without the afliftance of heat, though bylong maceration it becomes at laft fomewhatfoftened, and then dilfolves .in ammonia makinga blood-red liquor. But if nitric acid is heatedon this albuminous cartilage it is rapidly dif-folved with difcharge of much nitrous gas.

With cauftic fixed alkali it is readily diffolvedinto a perfect animal foap, and during theprocefs much ammonia is given out. Acidsagain feparate the albumen from this foap un-changed. This charadler is much depended onby Mr. Hatchett as an argument for its affinitywith albumen and difference from gelatin.

It is alfo extremely flow of putrefaction, re-maining long unaltered even in warm and moilt

fituations, and in this too it ftrongly refemblescoagulated albumen.

We may therefore enumerate as the foftparts of bone, gelatin, oil, albumen, and water.

A Swedilh chemilt, Gahn, was the firft whodifeovered the true nature of the earth of bones.This earth is produced by burning bones of anykind in open velfels, or in the large way in theopen air, till every thing volatile and inflam-mable is diflipated; and there then remains ahard porous white earthy fubftance, retaining-the fhape and fize of the original bone, andgenerally amounting to from one-half to a thirdof its weight. This earth is eafily reduced topowder, and fuffers the moll intenfe heat with-out further change. It is found to confift almoftentirely of Phosphat of lime , -with eiecefs oflime , or what is elegantly termed, according toDr. Thompfon’s fyftem of nomenclature, Sub-phofphat of lime, mixed with a fmall quantity offulphat and of carbonat of lime. Meffrs. Fourcroyand Yauquelin have likewife detected a fmallportion of phofphat of magnefia in the earth ofthe bones of all claffes of animals except thehuman.

Many of the chemical properties of the earthof bone will be deferibed under the articlePhosphat of lime and Phosphorus, for thepreparation of which laft it is peculiarly con-venient. For the analyfis of bone the following-particulars Ihould be noticed.

Phofphat of lime exifts in two ftates, in onewith an excefs of calcareous bafe as in the bone-afh, in the other with excefs of phofphoric acid.When fulphuric acid is added to the bone-aft),only a partial decompofition takes place, andthe phofphat by giving up a part of its lime tothe fulphuric acid is changed to the acidulous-phofphat of lime. This laft, when dried andheated red hot, runs into a greyifli white femi-opake glafs, and when ftrongly heated withcharcoal the excefs of acid is decompofed there-by, and the product is phofphorus, whilft thephofphat of lime, now deprived of its excefs ofacid, remains unchanged.

Phofphat of lime in any ftate is foluble withextreme eafe in every acid, even by the carbonicwhen fufpended in water and expofed to aftream of this acid gas ; hut it does not appearto be at all decompofed by any acid whofe cal-careous fait is a foluble one. Thus the nitric,muriatic and acetous acids, when digefted withthe earth of bones, Amply diflolve the phof-phat of lime, and again let it fall unchangedon the addition of any alkali, cauftic or car-bonated ; and therefore the precipitate even