15 I T 



far this principle modifies tluir medicinal powers. The ni- 

 tratcd f.lvcr is of tl.is kind, a fait cftccmcd to be a very 

 powerful tonic, taken internally in fmall dofes. Some ot tUc 

 faline combinations oftnagncfia have llie fame tallc, and it is 

 polTibly on this account, that the fulphat of magneha vvill 

 often be retained by very irritable llomachs, when other 

 faline medicines are reiccted. For the pharmaceutical pre- 

 parations of the feveral bitters, fee the rcfpctiive articles; 

 as Galium, Omiffui, Columlo, 'dc and that ot Butcr Extract. 

 DITTOUK, in Onikhol'isy- See Bittern. 

 BITITIJERCULATA, in /^n/oPK.%_v, a fpeciesof Cas- 

 sioa, of a brown colour, with a white margin ; wing-cafcs 

 fpolted with black, and a fingk tubercle at the bafeot each. 

 A native of Cayenne. I'abricius. 



BITUBERCULATUS, a fpecics of Cupxulio, that 

 inhabits New Zealand. This is of a ferruginous colour ; 

 thorax length of the wing-cafcs, and dotted, with two tu- 

 bercles on tlie back. Fabricius. 



BITUBERCULATUS, a fpecics of Cryptocephalus 

 {Crioccns), that inhabits Africa. It is fulvous ; wing-cafes 

 pale, entirely bordered with fulvous. Fabricius. 



BITUMEN, Bilume, Fr. The bitumens, properly fo 

 called, form a fpecies of compound mineral inflammables, ot 

 which the following are the charaders. £. By cxpofure to 

 the air, and the apphcation of heat, they burn with a flame 

 more or lefs vivid, and leave fcarccly any refidue. l. By 

 dellruiflivc diilillation, they yield a liquid acid, but no am- 

 monia, a variable but fmall proportion of charcoal being left 

 behind in the retort. 3. They are either liquid, or capable 

 cf being rendered fo by a moderate degree of heat. 



Bitumens may be divided into two families, the non-elatlic 

 and elaftic. To the former belong naphtha, petroleum, 

 mineral tar, mineral pitch, and afphaltum ; to the latter be- 

 lon'f mineral caoutehou, and fubcriform mineral caoutcliou. 

 § I. JVoii-E/iiJlic Bitumens. 

 Naphtha, Bergnaphtha, Naphte, Bitumc liqu'uk blanch- 

 itre, is a fub(\ance of a light brown, or wine yellow 

 ei>lour, pcrfeflly fluid and traufparent. It is the lightcll 

 of all liquids its fpecifjc gravity being =0.708 to 0.732 ; 

 it has a ftrong penetrating bituminous fmell ; it takes 

 fire with great readinefs, and burns with a bluifli yel- 

 low flame and copious blnck fmoke, leaving no refidue. It 

 may be reftilied bv dillilhition with water, in the fame manner 

 as the eflential oils, and then becomes colourlefs, and weaker 

 in it5 odour. It does not combine in any conflderablc de- 

 gree with either water or alcohol, but unites ealily with 

 ether, with turpentine, with caoutehou, and the effential 

 oils. Wlien rubbed with the cauflic fixed alkalies, it forms 

 a kind of Starkey's foap. The concentrated fulphuric and 

 nitric acids are decompofed with vehemence upon it, con- 

 verting it into a folid refinous fubllance folnble in alcohol. 

 Even the pnre!l naphtha, when cxpofcd to the air, becomes 

 firil of a yellow, and then of a browniflr colour, acquires a 

 fomewhat vifcid confidence, and thus pafles into petroleum. 

 Naphtha is procured for the moll part from very copious 

 fpHi:gs of this fubllance at Baku on the Ihore of the Cafpian 

 fea, where it is burnt in lamps inllead of oil, and is ufcd me- 

 dicinally both externally and internally in rheumatic and other 

 complaints. It is alfo met with in Calabria and fome parts of 

 Italy. 



Petroleum, or Rod-oil. Erdohl, Ste'm-ohl. Petrole. 

 The colour of petroleum is a blackifli or reddilh brown ; it 

 is fluid, though fomewhat vifcid ; it is almoft opaque, s unftu- 

 •us to the touch, and exhales a llrong bituminous odour ; its 

 talle is pungent and acid. Sp. gr. 0.847, 0.854. Petroleum 

 may be reftified by dilliilation with water, in which procefs, 

 the carbon, which thickens and colours it, is left behind in the 



B I T 



retort, and a colourlefs fluid comes over, pofTefTcJ of all the pro-* 

 perties of naphtha. When petroleum is diililled /v7-_^, there 

 firfl. arifcs fomc naphtha, then a watery empyreu.natic acid, 

 and lalUy a thick dark coloured oil, a fpungy coal remaining 

 in the retort. In its combinations with, and chernical aftions 

 on other fubllances, it perfeAly refenibles the preceding fpe- 

 cies. It is found wherever naphtha is, and in many other 

 places among flratilied mountains, in the vicinity of coal. 

 In England, Coalbrook dale, and Pitchford in Shropfliire, 

 are the principal places where petroleum is found ; at the 

 latter place extenfive ftrata of fandllone are faturated with 

 petroleum, and the naphtha, procured by dilliilation of the 

 Hone, is fold under the name of Betton's Brililh oil, and i> 

 tUeemed an aftive remedy in ftrains and rhcunwtifm. 



Mineral Tar, Barbadoes Tar, Bcrgihicr, GouJron- 

 ni'meral. This fubllance diff"ers from the preceding only in 

 degree ; it is more vifcid, more opaque, of a darker colour, 

 and, when dillillcd, leaves a larger carbonaceous refidue. It 

 is found native together with petroleum, and may alfo b'3 

 procured by the dilliilation of coal. 



Mineral Pitch, Maltha. The external chara£lers of 

 maltha are extremely fimilar to thofe of common pitch ; 

 when heated, it emits a llrong unpleafant odour. In cold 

 weather it may be broken, and exhibits a vitreous luflre ; 

 but when warm, it is foft and tenacious. 



Asphaltum, Schlachiges Erdpeih, /IJphaUc. The colour 

 of this fubllance is black or brownifli black ; it is light and 

 brittle ; when broken, it difplays a conchoidal fratture and 

 vitreous lullre ; it has little or no odour, unlels it is nibbed 

 or heated. It is coni'idcrably inflammable, melts eafily, and 

 burns away without leaving any refidue. It is principally 

 found on the fliores of the Dead Sea, in Syria, and in the 

 ifle of Trinidad in the Well Indies. 



The principal ufe of afphaltum is as an ingredient in cer- 

 tain varniflies, efpecially that ufed by the copptr-plate en- 

 gravers. 



§ 1. Elitjlic B'ttunwns. 



Mineral Caoutchou, Elajlichcs Erdpech, Po'ix niiiif^ 

 rale elajlique. The colour of this fubllance varies from 

 yellowilh brown to olive brown and blackilh or reddilli 

 brown. The light coloured is often in a femifluid llatc, and 

 adiieres to the fingers ; the olive brown is folid and elallic ; 

 the blackirtr and reddiili brown are hard and little elallic. 

 It occurs ilalaftitical, or invcfting, or in mafl'cs. Its Ip. 

 grav. in the foft varieties is about = o.y, and in the liardell 

 and leaft. elafl:ic is = 1.2. It palFes into afphaltum. 



It is partly foluble in fulphuric ether; but the refidue of 

 the lolution, after evaporation of the ether, is not elallic ;. 

 thus forming an eifential difference between the vegetable 

 and mineral caoutchou. 



This fingular mineral has been hitherto only found in the 

 cavities of a lead mine, near Cailleton, in Derbylhire, called 

 the Odin mine, accompanied by afphaltum. 



SuEERiFoRM Mineral Caoutchou. This fubllance, 

 when recently cut, exaftly refembles fine clofe cork in its 

 colour and texture ; but by expofure for a few days to the 

 air, it becomes of a pale reddiili brown colour. It is alfo 

 fometimes found friable, and paffing by decompofition into 

 an ochraceous powder. It has only been found in a rivulet 

 near the Odin mine, whence the preceding is obtained, and 

 appears to difl'cr from it, merely by being penetrated with 

 water. It occurs in nodules of various fizes, forac weighing 

 upwards of 1 3 pounds, the nucleus of which is very common- 

 ly the brown perfectly elaftic mineral caoutchou. Fourcroy 

 Syfl:. vol. viii. Brochant. Mineralog. vol. ii. p. 58. Diet, d' 

 Hill. Nat. art. Bhunies. Gren. Syft. Handbuch. vol. iii. 

 p. I. Hatchett on iiitmneiis jn Liuuaan Tranf. 



BITURIGES, 



