B O R 



B O R 



tRe alembic, is at prefent but little prairifed. The mod ex- 

 peditious .'iiid economical way o( preparing the boracic acid, 

 is by precipitation ; for this purpole, take a boiling hot fa- 

 tur;!ted folulion of purified boraK in water, and add to it, by 

 a little at a t;mf , fo much fnlphuric acid as to make the foiu- 

 tion (lightly acidulous. The liquor, when cold, will be 

 found to have depofittd a confiderable quantity of thin cryf- 

 talliiJC plates of boracic acid, and more may be obtained by 

 fuccedive evaporation and cooling, till cryihils of fulphated 

 foda begin to make their appearance. Tlie fulphuric acid 

 is on feveral accounts preferable to any other for the dccora- 

 pofitiou of the borax ; yet the nitric, muriatic, or even the 

 acetous acids may be made iilc of. and will cffeft a fepa- 

 ration of the boracic acid from the foda with which it 

 was united in the borax. The proportion of acid obtained 

 by precipitation amounts, according to Beaum.c, to nearly 

 one half of the borax made uic of ; and it is this kind of bo- 

 racic acid that has been nfed by moil chemills in their expe- 

 riments on this lubllanee. The precipitated acid is, how- 

 ever, by no means pure, as it retains, accordii^g to Cadet, 

 a portion of the acid made ufe of in its prccipitatioQ, and 

 confills, according to Beaume, of about 

 ^6 boracic acid 



14 an impure unfublimable fait 

 30 water of cryllallizatioii 



Sublimed boracic acid is in the form of very minute thin 

 plates, with a fhiniug filvery luftre, and remarkably volumi* 

 nous in proportion to its weight. Tlie cryftallized acid has 

 the fame general appearance, only it is in larger plates, and 

 cf confiderably greater fpecilic gravity. 



The tafte of boracic acid is ilightly fubfaline ; it reddens 

 fyrup of violets, but exhibits very feeble acid charaftcrs. 

 It is very difficultly foluble in cold water, and requires a 

 confiderable proportion of hot water ; as the hot folutioii 

 cools, it depofits in cryrtalline plates nearly the whole of the 

 acid which it had taken up. Alcohol takes up a larger 

 quantity of this fait than water does, and burns in confe- 

 quence with a green flame. On this account boracic acid 

 has been fuppofed by fome chemills to contain copper. But 

 if a piece of paper is dipped in the alcoholic folution, and 

 then dried, it will burn with a deep yellow flame ; hence it 

 is obvious, that the green tinge in quellion is only caufed 

 by a mixture of the yellow flame of the boracic acid with 

 the blue one of the alcohol. 



When boracic acid is heated to rednefs in a filver crucible, 

 it becomes firit of a party confillcnce, and then melts into a 

 tenacious glafs perfectly colourlefs and tranfparcnt. By ex- 

 pofure to the air, this glafs becomes opalcfcent, but docs 

 not undergo any other change ; it is foluble in water, and 

 may be obtained, by cooling and evaporation, in the Hate of 

 cryftalhne plates as before. When fiifed in an earthen cru- 

 cible, it diifolves fome of the earth, and forms a Itmi-tranf- 

 pareiit glafs confiderably lels fufible than the pure acid; and 

 when diffolved in water, and evaporated, it becomes a gela- 

 tinous mafs, fupcrficially covered with a few cry Hals of bo- 

 racic acid. 



Neither the oxygenating nor deoxygenating procefles ap- 

 pear to have the fmallcft eff^eft on this acid ; and all attempts 

 to raife it to a higher degree of oxygenation, or to decom- 

 pole It, numerous as they have been, have not been attended 

 with the fmallell fuccefs. It unites in the moirt way by fingle 

 afiinity with the cauftic alkalies, and by compound affiuity 

 alio with the earths and metallic oxyds ; its attradtion, how- 

 ever, ic fo feeble, that it is incapable, when in folution, of 



didoilging even the carbonic acid from its bafis. Rut weak 

 as boracic acid is in the moill way, its fixity in the fire ena- 

 bles it to feparate, in a high heat, the iiilphnric, nitric, 

 muriatic, and all the other volatilizable acids from their 

 bafes, forming with them a genus of falts called borau, 

 none of which, exec))! the fub-borat of foda, or common 

 Borax, has hitlicrto been made the objedl of chemical 

 invfftigation. 



I'onicic acid, befides being obtained from the decompo- 

 fition of borax, is alfo found native in certain hot ipriiigsand 

 lakes in Tufcany. It is not applied to any medical, chemi- 

 cal, or cco'.ionucal ufe. 



BORACITE, Bora%tt, Ww-fdjlcm ; Ma^mfte boratu, 

 Hauy. The colour of this mineral is yiUowifll, fmoke or 

 afli-grcy, pafiiiig into greyilh or greenifli-white. It occurs 

 in fmall cubic cryllals truncated on the angles. The cryrtals 

 are for the mod part opaque, fome are feini-tianfparent, and 

 a few of the fmallell are entirely tranfparent. Their lullrc 

 internally is conliderablc, and of the vituous kind. The 

 fracture is fmall and flat conchoidaT, pafHng into uneven and 

 fpliiiterv. The cryftals are often corroded more or lefs, and 

 then are eafily pulveiizable ; bat when perfeft, they iirc 

 hard enough to give brilk and lively fparks wiitn iliuck 

 againd the fteel. Sp. gr. i^fi. 



The boracite, wlicn expofed to a full red heat, becomes 

 opaque, and lofes about \ per cent, of its weight, but un- 

 dergoes no other change ; when intenfcly heated in a clay 

 crucible, it runs into a yellowidi g'afs. It is entirely, though 

 with difliculty, foluble in muriatic acid by long digcllion. 

 According to the analylis of Wellrumb, it confills of 

 68 boracic acid 

 1,3.5 "'agnefia 

 II lime 



1 alumina 



0.75 oxyd of iron 



2 lilex 



96.25 



Some later experiments, however, of Vauquelin make the 

 proportion of lime to be much fmaller ; and it appears pro- 

 bable, that the only elfcntial ingredients of this mineral are 

 boracic acid and niagiielia. 



Boracite is found near Luneburg, in the duchy of Brunf- 

 wick, lining the lides of a vein in a hill of fulphat of hme. 

 Tlie cryllals from their fliape were known in tlie neighbour- 

 hood by the name of wurfelfpath, or cubic fpar, and were 

 fuppofed by fome mineralogills to be a variety of quartz. 

 The prefencc of boracic acid in them was not fufpefled, 

 till the analylis of Wcftriinib, publilhed in 178S, in the 

 Traufadlions of the Society Nat. Curiof. Emmerling. 

 Hduy. An. de Chim. v. 1 1 . 



BORAGE, i:i Botnm. See Borago. 



BORAGlNE.Ii, the n-nth order of the eighth clafs 

 of Jnffieu, of which he gives the following natural 

 charaflcr. C^/j-.v five-parted, permanent. Cvrolla molt 

 commonly regular. Stamens generally live. Germ Am- 

 ple, or four-lobed. Style one. Stigma either bifid, furrowed, 

 or liir.ple. Seeils moll frequently four, either in a capfule or 

 a berry; or elfe apparently naked, obliquely attached to the 

 llyle, and for the moft; part enclofed in the permanent calyx. 

 Coreulum without a perifperm. Stem in moll herbaceous ; in 

 a few, a flirub or a tree. Leaves alternate, often rough. 



The genera are thrown into live diviflons. i. Fruit, a 

 berrv ; item, a ftirub or a tree. Patagonula, cordia, ehrctia, 

 menais, varronia, tournefortia. 2. Fruit, one or two-cap- 

 fular, herbaceous. Hydrophyllum, phacelia, clllfia, di- 



chondra ? 



