B I T
It is nearly of the fize of the common heron ; its head is fmall and narrow ; its crown is black ; and there is alfo a black fpot on each fide, near the angle of the mouth. Its throat and fides are reddifh, variegated with black tranfverfe lines ; the neck is covered with very long feathers, which make it ap- pear much thicker and fhorter than it really is ; its belly is of a dufky white, with a caff of a brownifh red, and its back is variegated with a pale reddifh brown and black. It makes a very "remarkable noife, which it repeats either three or five times. It is heard only in the building time, which begins in February. The common people, from the Angularity of the noife, think the bird, in order to make it, fticks its beak in a reed, or in the mud. It is commonly found lurking in fedgy and reedy places, near the waters, and fometimes in hedges. Toward autumn, this bird flies very high in an evening after fun-fet, rifing with a fpiral afcent, till quite out of fight ; and as they rife they make an odd noife, not at all like their ufual note. This they repeat alfo very often, as they are on the wing in the night; and hence they are called by fome, tho' improperly, the tight raven. It builds on the ground, and lays five or fix esgs, which are roundifh, and of a greenifh white. When wounded, and going to betaken, it ftrikes at the perfon's eye, and ought carefully to be guarded againft. Ray's Ornithol. p. 208.
Bittern is alfo a name given to the brine fwimming upon the firft concreted fait in the falt-works ; this liquor is ladled off, that the fait may be taken out of the veffel, and is after- wards put in again, and affords more fait, which is to be fepa- rated like the reft, by ladling off the liquor a fecond time, and fo on. Boerbaavc's Chem. p. 104. n.
The bittern, according to Mr. Boyle, is a very faline, bitter, fharp, pungent liquor, which drains off in the making of fait from fea water ; or which remains in the pans, after the coa- gulation, and granulation of the purer, and more faline part, by boiling. Vid Beyle, Phil. Work. Abr. T. 3. p. 482 Collins Salt, and Fifh. p. 53. ^uine. p. 51. A bittern alfo runs, or oozes, from the heaps of follil fait at Limington, and Portfea in Hampfhire. Phil. Tranf. N° 377 p. 348.
Bittern makes the bafis of the fal catkarticum amarum, or Ep fomfalt. Phil. Tranf. loc. cit. See Epsom /i/r.
BITTERNESS (Cycl.)— According to Grew, Utternlfi is pro- duced by a fulphur well impregnated with a fait, either alca- line or acid, and fhackled with earth.
B I U
and fuccinum, or amber. Woodiu Nat. Hift. Engl. Foff. T. r, p. 165. See Gagates and Succinum. Bitumen is fuppofed the chief fuel of the fubterranean fires. Vid. Kirch. Mund. Subterr. p. 157. Lang. Epift. p. 737. Many have been fond of fuppofing all fea-water to contain a laro-e quantity of bitumen, and that it owes its bitternefs to this admixture; but this feems erroneous, fince we find that all fea-water contains a large quantity of bitter purging fait of the nature of what is fold in our fhops, under the name of lipfoin fait; and its bitternefs is of the very fame kind with the tafte of that fait.
That there are, however, bitumens mixed infeveral places with the water of the fea, is very certain. Barbadoes tar is found floating on the fea, being warned in great quantities from the rocks, and count Marfigli obferved fpiral filaments arifmg from the furface of the fea Marmora, near Conltantinople, which concreted into bitumen, exactly of the fame kind with. that he obferved at Zant, flowing from the fides of a bitumi- nous mountain. On fome of the coafts of Italy they fkim off a kind of liquid bitumen, or petroleum, from the furface of the fea. Some think that ambergreafe is a bitumen of the fea, and many travellers tell us of a fatty fubftance on the furface of it, that gives light in the night. Thefe various fubftances ratty impart various properties to the fea-water, in fuch parts where they are found to abound, and they may be common in many places, but they are certainly not found in all, nor is bitumen a neceflary ingredient in fea-water. Count Marfigli has in- deed proved, that a fpirit diftills from the moft common of all bitumens. Pit-coal will give water a bitter tafte, but fea- water is not yet proved to be impregnated with fuch a fpirit. On the contrary, when diftilled, it has no bitter tafte; there- fore marine waters are not impregnated with foch a volatile fpirit, but evidently owe their bitternefs to a fixed principle ; and it is very certain, that pit-coal cannot give this tafte, fince the waters which iffue out from among the ftrata of Sea- coal are never found to be bitter, tho' often ftrongly impreg- nated with iron.
All the bitumens are inflammable, and have this good quality in their burning, that they will do without a wick. Dr. Plot therefore conjectures, that the famous fepulchral lamps of the antients were contrived of thefe bitwnens, particularly of the li- quid kind, becaufe any thing that would require a wick, would be liable to its choaking up, and being deftroyed. See Lamps perpetual.
Hence it is that the bitterefl; plants ufually yield the greateft Bitumen, in a more particular fenfe, is reftrained to the af-
quantity of lixivial fait ; and that many diftilled oils, digefted with any ftrong acid, acquire a bitter tafle. Add, that the leaves of all fweet roots are bitter ; the fig-tree, which bears a
- fweet fruit, bleeds a bitter milk; and that the roots of plants,
Which bear a bitter italic, are not bitter, but hot. That the earthy parts contribute confiderably to the bitternefs of bo- dies, appears hence, that moft bodies of that kind are fixed ; or, if they do emit fumes, do not lofe their bitter tafte therewith. Vid. Grew, Difc. of tafte of Plants, c. 4. §. 12. Mr. Boyle obferves, that a fubftance bitter in the higheft de- gree, may be divided into two fubftances, the one extremely four, and the other infipid. This happens, when the cryftals of filver are diftilled by a heat fufficient to drive away all the fptrits from the filver. What remains is infipid, and whatrifes is highly acid. Works abr. Vol. 1. p. 541. The extinguishing, or removing of bitternefs, is called dulci- fying, fweetning, cjfe. See Dulcifying, Cycl. M. Bon has given methods of removing, or difcharging the bitternefs of olives and Indian chefnuts. Vid, Mem. Acad. Scienc. 1720. p. 600.
The bitternefs of fea-water arifes from the diffolution of the beds, or ftrata of bitumen ; as its faltnefs does from a diffolu- tion of the ftrata of fait. Marfigll, in Hift. Acad. Scienc. an. 1710. p. 33. See the article Sea. BITUMEN (Cycl.) — From the origin ,and inflammability of&- tumens, it appears they bear a near affinity to fulphurs, and are fuppofed both formed of the fame principles or ingredients; only differing in this, that fulphurs are harder and more brit- tle, bitumens more fatty and tenacious. Yet is not this di- ftin&ion ftrictly kept to ; divers other bodies being by fome naturalifts placed in one of thofe ranks, by others in another. Vid. Mcrcat. Metalloth. p. 82. and Budd, Elem. Philof. Theor. P. 2. ?. §. 33. p. 175.
Bitumens are of different kinds, arifing from the different pro- portion of the fulphur principle in them ; and the different intermixture of falts and earth, and other foreign matters with them. Mercat. ubi fupra. Verdr. Phyf. P. 2. c. 6. §. 6. p.470.
Bitumens are ufually divided into two fpecics, liquid and folid. Tho' fome diftinguifh three kinds. Gorr. Med. Defin. p. 60. voc. Aoiptzrto;. See the Cyclopaedia.
Dr. Woodward gives a different divifion of the Englifh bitu- mens, or bituminous foffils. The firft are thofe of a more lax I coarfe conftitution j and which, when wetted, yield
phalios, otherwife called bitumen Judaicum. Mercat. Metalloth. Arm. 5. c. 2. p. 81. Caji. p. ic6. See Asphaltos, Cycl. and Asphalta, Suppl.
Bitumen b : bleamt?n, in mineralogy, a name given by Bocco- ne and others to a peculiar fpecies of bituminous foflil, which is flexile while in the earth, a property very fingular in a fofiil not of the talky kind, as this evidently is not. It is a ftony fubftance, fmeliing like the common bitumens, and compofed of a very great number of thin plates, laid evenly and regu- larly on one another. It has its name from the place where it is found, which is the Hyblrean mountains of Sicily, near Milelli, neighbouring upon the town of Au^urta and the an- tient Megara. When burnt in a candle, the bituminous fmell is perceived very ftrong ; and the ftone, though when firft taken up it be flexible like paper, yet in time it hardens, and becomes brittle like other foflils of that lax confiftence. There are found whole hillocks covered with it. They do not ceafe to bear plants and herbage for this, the roots of the grafs, &c. infinuating themfelves between the lamina? of this ftone, and getting good nourifhment there. Phil. Tranf. N° 100.
BPrUMINOUS, fomething that relates to, or partakes of, the nature and qualities of bitumen. See Bitumen. All bituminous bodies are oftenfive to the head a . Their fmell or ftench makes the epilepfy difcover itfelf b . — [ a Lang. Epift. Med. 1. 2. b Plin. Hift. Nat. I. 35.0. 15. Lang. I. 2. ep. 7^. See Epilepsy.
Naturalifts difcover a bituminous quality in the fea-water, which it derives either from bituminous exhalations out of the body of the earth, or from fprtngs and rivers, which import liquid and other bitumens into the ocean. It is to this bituminous mixture the bitternefs of fea-water is afcribed by fome. Boyle, Phil. Work, abridg. T. 3. p. 221, feq. See Bitumen.
BIVALVE, in the hiftory of fhell-fifh, the name of one of the three general claffes, the other two being the univalves and the multivalves. The bivalve fhells are thofe winch confift of two pieces or feparate fhells joined together by a cardo or hinge. Thefe are a lefs numerous clafs than the univalves, and have been arranged by a late accurate French writer under fix ge- nera. Thefe are: i.Theoifters. 2. The change. 3. The mytuli, or mufcles. 4. The cardiform fhells. 5. The pec- tines, or fcallops. And, 6. The folcns, or razor-fhells. For the characters and fpecies of each of thefe, fee their feveral heads, Ostrea, Chama, c3V. Hift. Nat. Eclair. T. 2. P- 235-
^ofier, or pitchy matter : Such are the lapis pieeus, or pitch- 1 BIUMBRES, in geography, an appellation given to the inha- n;6nc, the fopisjzmpelites, obfidtanus orcanel, and the liihan- J bitants of the torrid zone, by reafon, at two different feafons
of the year, their fhadows are projected two different ways.
thrax or coal. The fecond of a more denfe and fine conflitu- I tioiij and which yields an oil: Such are the gagates, or jet d
Wolf. Lex. Math. p. 262,
The
