BON 



the water, and on cooling concreted into the confidence of 

 fuet. The haunch bones yielded about one eighth of fat. 

 The utmoft economy of bones, therefore, when ufed as 

 human food, may be obtained in the following method. 

 Fii-ll chop the fredi bones into fmall pieces, and extraft the 

 fat in the way jull mentioned ; then dry the bones, and 

 powder, or reduce them to a fine palle, by fome pretty 

 ilrong mechanical power ; and boil them with about ten 

 times their weight of water, for fome hours, till half the 

 water is wafted, more or lefs according to the kind of bone ; 

 the joint and thick bones making a richer jelly than the thin 

 bones, and tlierefore requiring lomewhat Icls boiling down 

 to make a jelly of a determinate conlillence. 



M. Prou'.l finds that this proportion of water is fufficient 

 to leave a jtlly of about the fame richnefs as would be pro- 

 duced by diffolving one oimce of bone jelly, dried to the 

 confillcnce of portable fonp, in thirty-unc ounces of water, 

 and makes a jelly of a very agreeable dej^rec of richnefs. 

 The extraftion is much afTifted by ufing an n-on vcflTel wit'n 

 a elofe lid, to give a heat fomewhat greater than that of 

 boiling water, thougii not to the degree of a Papin's 

 digeilcr. 



In all the above experiments on the extraftion of jellv and 

 fat from bones, tlie ui'cooked bor.e is underllood to be ufed. 

 The b.>nes of lo'tlcd me.^'t, tliongh deprived of fome of their 

 extractive matter, are llill rich in niitrin-.ent ; but ronjnng ren- 

 ders them entirely unfit for tliis pnrpole. 



The earthy part, whieli compofes on an average about 

 half the weight of the larger bones of animals, was difeo- 

 vered firft by Gahn, a Swedifh chemift, to confid of the 

 ph-.ifphoric acid united with a large proportion of lime. It 

 will be more minutely defcribed under the article Phos- 

 PHAT of Lime ; and ii i^ the molt convenient fubftance from 

 which Phosphorus is prepared. It may here be men- 

 tioned, that the llronger acids, fnch as the fulphuric or ni- 

 tric feparate a part of the lime from tins earthy fait, but 

 onlv a part, for when fulphuric acid is added to bone afh, 

 fulpliat of lime is formed in great qnautitv, mod of which 

 remains at the bottom of a fupernatant liquor, confifting of 

 a great excef;. of phofph(n-ic acid united with a fmall portion 

 of lime, and alio tome fulphat of lime diifolved therein. It 

 fhould be remarked in the analyfis of this fait, that this acid 

 phofphat of lime, is not decompofcd by any fingle acid, 

 nor even by the pure or carbonated alkalies ; for, on adding 

 the latter, the precipitate is not carbonated lime, but ftill 

 the pholphat. 



This earthy fait, when in foh.ilion, is, however, entirely 

 decompoled by the nitrat or acetite of lead ; the lime re- 

 maining d'fiolvcd in the liquor by the nitric or acetic acid, 

 and the pliofpliat of lead torming an infoluble precipitate. 

 Phofphat of lead is dilliugnifliable from fnlphat of the fame 

 metal by bcin^ readilv f .luble in n'tric acid. If t!ie phof- 

 phat is forinkled on hot charcoal, the lead is reduced, and 

 the Uinu;:oefncfs and peculiar fmell of phofphor\is are per- 

 ceivable. Tl;e phofphat of lime is equally dillingm'fhable 

 from the fulpli.u i:f lime by being very folubie in moft acids, 

 tven when dilute. 



Much light has b.'en thrown on the analyfis, and with it 

 the phyfieal (Iruetureot bone, ard ot nioll other of the hard 

 fupuorti:!g or p/oteCting parts of the body, by the accurate 

 and numerous expeiimeiits of Mr. Hatchett, whofe re- 

 fearches into thcle fubjecfs are admirably calculated to Ihew 

 the extreme advantage wh'ch pliyfiology derives from the 

 labours of the chcmill, when affilled by accurate knowledge, 

 and guided by a philofophical fpirit. 



When bones, boiled or frelh, are fteeped in any acid, a 

 (light effervefcence is perceived, and they prefently are ren- 

 dered foft and flexible by the gradual abllrattion of the 



BON 



earthy bafis (chiefly phofphat of lime), which becomes dif- 



folvcd in the acid. If the bone be previoufly boiled for a long 

 lime in water, its gelatin is removed by this liquid ; but 

 if the bone is in its natural ftate, the gelatin alfo is gradually 

 diflblved in the acid, rendering it yellow and fomewhat tena- 

 cious. The infoluble refidue (except in a few kinds of bone, 

 fuch as the enamel of the teeth) is either a membrane or a 

 fpongy cartilage, retaining the form of the original bone ; 

 for, in the procefs of oflification, membrane or cartilage 

 forms the firft bafis or rudiments of bone, which is after- 

 wards completed by the gradual depofition of the earthy 

 falts. Though pliofphat of lime forms the chief ingredient 

 in the earth of bones of all animals, a fmall portion of ful- 

 phat of lime is mixed with it; and Mr. Hatchett has detected 

 alfo a little carbonate of lime. The carbonic acid of this is 

 that which occafions the (light effervefcence during the adioy 

 of the acid ; the lime remains difToIved in the acid after the 

 precipitation of tlie phofphat of lime by pure ammonia. A 

 carboniited alkah then precipitates it together with the now 

 decompufed earth of the calcareous lulphat. 



We have thus (hewn the great conllituent parts of 

 bone to be gelalin, folubie by boiling in water, and giving a 

 line clear jelly ; oil, feparable, during the boiling, by rifing 

 to the top of the water, and when cold concreting into a 

 fuet ; phnfbhut of Um^, fohible in ddute nitrous muriatic or 

 acetous acid, and precipitable thence by pure animcuiia ; 

 iome filphat of liiiie ; a little carbonate of lime ; and a mcm- 

 branous or cartilar'hwus fnbllance, retaining the form of the 

 bone after every thing elfe has been extracted by water and 

 an acid. 



For a highly probable opinion on the nature and ongin of 

 this membrane or cartilage, we are indebted to Mr.Hatchett, 

 who ha> fliewn a number of charaftcrillic marks, in which 

 it moll ftrongly refembles infpiifated albumen, and by which 

 it differs from gelatin. The chief of tliefe are the fol- - 

 lowing : 



When dry, it is femi-tranfparent, like horn, and more or 

 kfs brittle. In this ftate it refifts the aition of water very 

 powerfully ; for when boiled for many days with this fluid, 

 a fcarcely perceptible precipitate is given by nitro-muriat of 

 tin ; a tell of difiolved albumen. In this it Itrikingly re- 

 fembles coagulated albumen, and as pointedly differs from 

 gelatin, which, as we have feen, is readily extraiSlcd by 

 water even from the dryell and hardeft bones. 



This bony membrane, as well as albumen, is fcarcely 

 afted on by cold muriatic and fulphuric and dilute nitric 

 acids, which laft readily extrafts gelatin from bone. How- 

 ever, after an immerfion in thefe acids of fome weeks, the 

 bony cartilage, when taken out and fteeped in ammonia, 

 gradually diffulves into a blood-red liquor. But if the nitric 

 acid is heated, the albuminous membrane is rapidly diifolved 

 with the copious difcharge of nitrous gas. 



With caullic fixed alkali, the bony membrane or cartilage 

 is readily diffolved into a perfeft animal foap (a lliong mark 

 of refemblance to albumep, and difference from gelatin), and 

 during the procefs much ammonia is given out. Acids 

 again feparate the albumen from the foap, unaltered in che- 

 mical properties. 



Lallly, the bony cartilage is extremely flow to enter into 

 a ftate of putrcfadion, though kept moift and warm for 

 many weeks; and in this too it refembles coagulated al- 

 bumen. 



Therefore, in addition to the above-mentioned conftituent 

 parts of bone, we may add nlbumcn, in a condenfed ftate, 

 forming the fubftance of the original cartilaginous or mem- 

 branous ftrufture, both of all the organized bones, and, as 

 Mr. Hatchett has alfo ftiewn, of moft of the hard parts, 

 which ferve for the covering, proteftion, and arming of 



almod 



J 



