Page:Cyclopaedia, Chambers - Supplement, Volume 1.djvu/370

 BRA

BRA

BRASMA, in die medical writings of the antients, a name gi- ven by Diofcorides and others to a light, empty, and good for nothing kind of black pepper. This was no peculiar fpecies cf pepper, but, as John Bauhine has well obferved, it was the fame with the pepper we now frequently meet with, which has decayed upon the plant. Diofcorid. 1. 2. c. 189.

BRASS (Cycl.) — The word brafi teems to have been formed from bracium, a cant term among alchemifts for copper. Rul. Lex. Alch. p. 106. voc. Bracium.

Brafs amounts to the fame with what is otherwife called kitten, or latton ; by the French leton, or laiton, and fometimes culvre jaune, or yellow copper a ; by the Greeks, opei^a*o^ and the Latins, orichakum*, or aurichalcum c. — [ a Savar, Diet. Com. T. 2. p. 502. voc. Letin. Trev. Diet. Univ. T» 3. p. 1390. b Vid. Cajl. Lex. Med. p. 547. voc. Orichakum. ' c Id. ibid. p. 93. voc. durichalami.'}

Brafs is made in divers manners ; the moft ufual is that men- tioned in the Cyclopedia. See alfo Neri, Art. Vitriar. I. r. c. 20. Mar. Obferv. on Neri, p. 299, feq. Hought. Collect. T. 2. N° 258. p. 190. Feiib. Print Archit. I. 2. c. 5. p. 240. "Junck. Confp. Chem. tab. 42. p. 1058. Kirch. Mund. Subterr. I. 10. fee. 4. c. 9. T. 2. p. 218. Phil. Tranf. N° 260. p. 474. It. N°200. p. 735.

The calumin does not enter the copper under its earthy ftate, but is firft converted by die phlogifton into the form of a me- tal: Henkel, it is true, imagined that only the mercurial part of the calamin was added to the copper, without any of the ful- phur j but this opinion later chemifts fecm to have fufficiently refuted. Vid. Junck. Confp. Chem. tab. 42. p. 1061, feq. Brafi may be cleanfed, firfr, by rubbing it with a cloth dipped in equal quantities of aqua-fortis and common water; then with an oily cloth, and laftly with a dry one dipped in lapis calaminaris.

Brafs is tinged of a gold colour, firft, by burning, then dif- folving it in aqua-fortis, and, laftly, reducing It to its metal- line flare. It may be whitened by heating it red hot, and quenching it in water diftilled from fal-armoniac and egg- fhells. It is filvered, or coloured fuperfidally white, by rub- bing it with balls made of filver difiolved in aqua-fortis, with powder of white tartar, fufficient to abforb all the moifture thereof.

Brass, in a more extenfivc fenfe, includes copper, and all the mixtures or alloys thereof with other minerals. In which fenfe, brafs amounts to the fame with the Roman ess, and the French airahu

Inltead of calamin, brafs is fometimes made of copper with zink; which is the fineft fort, and that which, on account of its beautiful golden colour, is called bath-metal, or princes-me- tal*. M. Homberg has even contrived a method of making brafs without either calamin or zink, by amalgamating the copper, which at the fame time difpofes the metal to receive gilding, which, in the ufual method, it is not eafily fufccptible of b.„ [* Boyle, Pbilof. Works, Abr. T. 2. p. 100. Stahl. Phil. Princ. Chem. P. 2. fee. 4. p. 335. «> Du Ham. Hift. Acad. Scienc. 1. 6. fee. 6. c. 4. p. 371. J

Brass, in antiquity. — Brafs having been in ufe before iron, arms, in the primitive times, were made of it ; which, ac- cording to Tzetzes, they fo tempered, as to render extremely hard. Hefiod fays exprefsly, that armour and other utenfils were then of brafs, becaufe iron was not yet in ufe. Hefiodt Epy. 1. T.

Macrob'ius fays, that the antients employed brafs in many of their facrifices ; and that when the Tufcans defigiied to build a new city, they marked out the circumference thereof with a plough-fhare made of brafs ; and that the Sabin pritfts cut their hair with brazen fciflars. Servius, in his remarks on the firfr. book of the ./Eneid, affirms, that the priefi of Jupiter was ne- ver {horn but with fciffars of the fame metal. 7'he antients alfo, according to die Scholiaft on the fecond Idyl of Theocri- tus, employed brafs in all their expiations, as eflcemino- this metal very pure; on which M. de Meziriac makes this re- flexion, that if the Scholiafl's reafon be jufr, the method of our antient druids was better, who fhore their holy locks with golden hooks, according to Pliny ; for that doubtlefs gold is purer, nobler, and more perfect than brafs. Plin. Hift. Nat. ]. 16. cap. 44.

Of late days, fmce fearches have been made in the north, and efpecially Jutland, many antient monuments have been difco- vered, in which were found brazen armour, as may be feen by the DifTertations of M. Mellem, Sperlingius, Rhodius, Schach- tius ?, &c. M. Sperlingius, indeed, docs not take them for armour, but for the figures of arms, which, according to this antiquary, the antient Goths always bequeathed to their heirs. M. Mellem and Rhodius maintain, on the contrary, that theft are the arms themfelves; which opinion Tacitus alfo counte nances b : and though fome of thefc arms be of ftone, particu- larly hatchets and knives, we may gather from the inhabitants of America, who arm their darts with fharp ftones, and ufe them as our workmen do inftruments of fteel, that the barba- rians of the north had formerly arms and inftruments both of ftone and brafs, before iron was known, or at leaft common among them. We may add, that the Scriptures mention mir- rors of brafs, ufed by die women even in Mofes's time c.

[■'■ Vid. Nouv. Liter. Mar. Bait. 1699. p. 88. an. 1700. p. 14,24, 333. fc Tacit* deMorib. German, cap. 27. Bartho-

lin. Antiq. Dan. 1. 2. cap. 13. Hart. DifT 13. Rer. PrufE 1 1.6. Disburg, P. 3. Chron. Pruff cap. 5. c Trev. Diet. Univ. p. 244. voc. Airain. Phil. Tranf. N° 322. p. 394. Pott. Archjeol. Gn-ec. 1. 3. c. 4. T. 2. p 20, feq.] We meet with divers antient fpecies and denominations of brafs ; as,

Cyprian Brass, Ms Cyprium, a copper produced in the ifland of Cyprus.

Dodonean Brass, /Es Dodoncum, that ufed in die facred cal- drons in the temple of Apollo at Dodona.

Corybantic Brass, /lis Cerybantium, denotes the brazen rattles ufed by the Corybantcs in the myfteries of Cybele.

Cajl Brass, Ms Ctddarium, that only melted, otherwife called pot-brajs, ets olariwn, and not malleable; being that whereof pans and kettles were made.

Hammered Brass, JEs Regulare, that capable both of being caft and hammered ; by which it flood oppofed to ess caldarimn.

Wrought Brass, Ms faclum, that manufactured into veflels and other works. Vid. Pitifc. Lex. Antiq. in voc. Ms.

Unwrought Brass, Ms infeflum, that ftill in the mafs, un- formed.

Hepa'ic Brass, Ms Hepatizon, that which is of a liver colour, or approaching thereto. Some confound this with the Ms Co- rinthjum ; others, with more probability, take it to be the fame with what the moderns call bronze.

White Brass, Ms Candidum, a purer and whiter kind of metal, faid to be found under the veins of filver, bearing fome ana- logy to the Venetian talc. Pitifc. ibid.

It is plain that the antients were acquainted with fome way of making copper white, as well as yellow. Virgil mentions orichakwn album, and the Greeks *.<.vxw k^x.^% j both which phrafes exactly exprefs white brafs. We have feveral ways of rendering copper white, at prefent as in our alchymy metal ; but they feem inferior to the antient way. See Crama.

Yellow Bbass, Ms F/avum, was our common brafs, prepared with cadmia, or lapis calaminaris.

Glittering Brass, Ms Pyropum, a fort which fhone or appeared firy, fo as to refemble a carbuncle. Pitifc. Lex. Ant. T. 1. p. 48. voc. Ms.

Some fufpect the tradition of the origin of Corinthian brafs, from the burning of Corinth, as a fable; which they account for, by fuppofing that the firft difcovery of the art of making copper into brafs was made by the people of Corinth, who found the calamin ftone in the plains of Peloponnefus ; at leaft, that if it were known to others, it was the Corinthians who made it in the greateft perfection. Atlas Marit. p. 78.

Brass, in the glafs trade. — Thrice calcined brafs is a preparation which ferves the glafimen to give many very beautiful colours to their metal. The manner of preparing it is this : Place thin plates of brafs on tiles on die Ieet of the furnace near the oc- chio ; let it ftand to be calcined there for four days, and it will become a black powder flicking together in lumps. Powder this, and fift it fine, and recalcine it four or five days more; it will then not ftick together, but remain a loofe pow- der, of a rufl'ct colour. This is to be calcined a third time, in die fame manner ; but great care muit be taken, in the third calcination, that it be not over-done, nor underdone ; the way to be certain of making it right, is to try it feveral times in glafs while melting. If it makes it, when well purified, to fwell, boil, and rife, it is properly calcined ; if not, it requires longer time. This makes, according to the different pro- portions in which it is ufed, a fea green, an emerald green, or a turquoife colour. Nej-i's Art of Gla r s, p. 42. Brafs, by a long calcination alone, and without any mix- ture, affords a fine blue or green colour for glafs ; but they have a method of calcining it alfo with powdered brim- flone, fo as to make it afford a red, a yellow, or a chalce- dony colour, according to the quantity, and other variations in the ufing it. The method of making the calcination is this: Cut thin plates of brafs into fm all pieces with fheers, and lay them ftratum fuper ftratum, with alternate beds of pow- dered fulphur, in a crucible; calcine this for twenty-four hours in a ftrong fire, then powder and fift the whole; and, finally, expofe this powder upon tiles, for twelve days, to a reverberat- ing furnace ; at the end of this time, powder it fine, and keep it for ufe. Ntri's Art of Glafs. p. 37.

The glafs-makcrs have aifo a method of procuring a red powder from brafs, by a more fimple calcination, which ferves them for many colours. The method of preparing it is this : They put fmall and thin plates of brafs into the arches of the glafs- furnaccs, and leave them there till they are fufficiently calcin- ed, which the heat in that place, not being enough to melt them, does in great perfection. The calcined matter, pow- dered, is of a dusky red, and requires no farther preparation. Nert's Art of Glafs. p. 41.

Brass Lumps, in mineralogy, a common name given by the miners and diggers of coal, &c. to the globular pyrites. This ftone, when kept in the air, often fends forth its efitorefcences of fait, in form of fmall and flender fibres, perfectly tranfpa- reut, and fometimes of near an inch long. The place where thefe ftones are expofed to the air, will greatly alter the figures and colours of their efflorefcences ; if they are laid in a cellar, the fhoots will he fhorter, and green, like the common copperas ; and if laid in die way of the funfhine, they will be white and dufty. 6 Both