413 



BRONCHOTOMY. 



BRONZE. 



414 



continuation of the goitre ; in one case for eight years, in the other 

 for five ; upon its disappearance pregnancy took place in both. Sup- 

 pression of the menses has sometimes caused its sudden appearance 

 and rapid development ; and it more rarely has originated during preg- 

 nancy and the puerperal states. Authors have added conclusive proofs 

 of its occurrence hereditarily, independently of endemic influence." 



It has bet n said to have an intimate connection with poverty and 

 bad food, the rich being comparatively exempt from it ; but on this 

 point the statements are conflicting. It has been very generally attri- 

 buted to water used as drink, and more especially to snow-water ; but 

 the disease occurs where there is no snow, as in Sumatra and several 

 parts of South America; the Swiss who drink snow-water are free 

 from the disease, while those who use hard spring-water are prone to 

 it. In his journey to the Polar Sea, Captain Franklin observed that at 

 a part where bronchocele prevails, the disease is confined to those who 

 drink river-water, while those who use melted snow escape. Mr. Bally 

 ascribes its frequency in a district in Switzerland to the use of spring- 

 water impregnated with calcareous or mineral substances ; and he 

 states that those who use not this water are free from both goitre and 

 cretinism. Dr. Coinder observed that the inhabitants of Geneva, who 

 drink the hard pump-waters, are those most liable to bronchocele. 

 Its prevalence in Nottingham is ascribed by Dr. Manson to the same 

 cause ; which also seems to occasion it in Sussex and Hampshire, in 

 the valleys of which counties it is frequently met with. 



It is unquestionably most frequent in low, moist, marshy, and warm 

 valleys ; even in the very districts in which it is endemic, the inha- 

 bitants of dry and elevated situations are exempt from it ; but it is 

 probable that the malaria of those places operates only as a predis- 

 posing cause, favouring the action upon the system of some unknown 

 agent. 



It is frequently connected with a tendency to scrofulous disease in 

 this country, and is found in conjunction with cretinism in the Swiss 

 valleys. [CRETINS.] 



One of the most efficient remedies for the removal of bronchocele is 

 iodine. It should be administered internally, and may be applied in 

 the form of ointment externally. Iron and quinine may be combined 

 with this treatment with advantage ; but above all things, pure air is 

 the moot important. 



Sometimes the larger forms of bronchocele resist all medical treat- 

 ment, and, threatening life by pressure on the air-passages, they have 

 been successfully removed by the surgeon's knife. 



BRONCHOTOMY. [TRACHEOTOMY.] 



BRONZE, an alloy of copper, tin, occasionally zinc, and a little lead. 

 For casting statues, bronze has been used from the most remote 

 antiquity. According to Pliny, this art was brought to a considerable 

 degree of refinement 700 years before the Christian era. Ancient 

 military weapons and tools were also frequently made of it. For the 

 latter purposes steel has superseded this alloy, and bronze, strictly so 

 called, is now used for little else than the casting of statues and medals. 

 Sell, ffttn, and speculum metal, all largely used, are however merely 

 varieties of bronze, and will be severally treated of in this article. 



The essential characteristics of a metal to be used for statuary pur- 

 poses are obvious. It must flow freely when melted and expand on 

 *'i]i,lifying, in order that the minutiae of the mould may be accurately 

 represented. It must be so tough and hard that it will be but little 

 affected by accidental blows, and be composed of such substances as 

 will yield an alloy on which the weather will have the least possible 

 influence. All these requirements are exactly fulfilled by bronze: 

 moreover, the slight action of air and moisture on this alloy by long 

 exposure give to the statues a greenish tint, that to the eye is more 

 agreeable than otherwise. 



The following are specimens of the proportions of copper, tin, &c., 

 which may be used in the manufacture of bronze ; they may be 

 slightly varied, according to the purposes for which the alloy is 

 intended : 



I. IT. III. 



Goppa 



Tin 

 Zinc . 



100 



VI 



100 



87-25 

 9-75 

 3-00 



100-00 



No. 1 is the formula recommended by M. Chaudet : a bone-ash 

 iii'nild furnishes a perfect impression that only needs polishing. No. 2 

 assumes ui antique appearance by age. No. 3 is an average of the pro- 

 portions now generally used for medals. The celebrated statue of 

 I.ouU XV. contained 



Copper . 

 Zinc 

 Tin 

 Le.d 



82-45 



10-30 



4-10 



3-1.5 



100-00 



I 



Specific gravity 

 8-482 



Small quantities of bronze may be melted in crucibles, large masses 

 on the hearth of a reverberatory furnace. The molten metal shoxild be 

 occasionally stirred to prevent separation into layers, and the whole 

 operation conducted as quickly as possible, to prevent waste of coppei 



and tin by oxidisement, and zinc by volatilisation. This effect may 

 also be prevented to a very great extent by covering the whole with a 

 ayer of small charcoal. 



Gun- or Cannon-metal. The best proportions of copper and tin for 

 :his alloy seem to be about nine of the former to one of the latter. 

 Zinc and lead are never added. A larger quantity of copper causes the 

 masses to separate on cooling into two layers ; this may be avoided by 

 very sudden cooling in thick iron moulds, or in water ; but large cannon 

 cannot be treated in this way. 



Bell-metal always contains a much larger amount of tin than gun- 

 metal. When suddenly cooled, it is soft, tough, and malleable, and in 

 ;his state may be turned in a lathe and worked with considerable ease. 

 By re-heating and slow cooling it is obtained hard, brittle, and sonorous. 

 Some of the best specimens of bell-metal consist of 



Copper 

 Tin . 

 Zinc 

 Lead 



22 



100 



II. 

 82 

 18 



III. 



80 



10-1 

 5-C 

 4-3 



IV. V. 



75 72-00 



25 26-50 



Iron, 1-44 



100-0 100 



No. 1 is very fusible and sonorous. No. 2 is the composition of the 

 Chinese yong-ijonijs ; it should be very suddenly cooled. No. 3 : old 

 English bell-metal. No. 4 : excellent for church bells. No. 5 : pro- 

 portions, according to M. Berthier, of the ornamental French clocks or 

 pendules. For similar purposes, a little zinc increases the sharpness of 

 the tone. 



Speculum metal, used in the preparation of specula for reflecting 

 telescopes, has still less copper and more tin than bell-metal. It fre- 

 quently contains also a little metallic arsenic, which is supposed to 

 render it whiter ; thus : 



Copper 



Tin 



Arsenic 



I. 



, 64-5 



32-2 



3-3 



100-0 



IF. 

 C6-6 

 33-4 



100-0 



III. 



100-0 



or(Cu lS n) 



The proportions in No. 3 were used by Lord Rosse in the manufacture 

 of his celebrated reflector. 



The materials of speculum-metal should be thoroughly incorporated 

 when in the melted state by brisk stirring with a wooden spatula, and 

 the mould so arranged that the bottom shall receive the intended upper 

 surface of the mirror ; this part will therefore cool first, and give the 

 most perfect casting. This variety of bronze is exceedingly brittle, a 

 slight blow, or the incautious application of even a gentle heat, causing 

 its fracture ; the polishing of specula must therefore be performed 

 with great care. For this operation, Mr. Potter recommends peroxide 

 of iron, prepared by precipitating sulphate of iron with ammonia, 

 washing the precipitate with water, and heating to dull low redness. 



Composition of varieties of ancient bronze : 



Tin . 

 Copper 



Tin . 

 Copper 

 Zinc . 

 Iron 



a 

 12 



100 



26-0 



71-0 



1-8 



1-2 



100-0 



6 



22-02 

 77-60 



89-02 



19-5 



80-5 



100-0 



I 



19-CG 

 80-27 



90-03 



97 



d 



20-74 

 73-00 



99-74 



A 



15 

 83 



a. Bronze from Celtic vessels, swords, and spears. (Clarke, ' Ann. 

 Phil.,' 7, 73.) 6. Arrow-head from an Egyptian tomb. c. Cast coffin 

 from Altai, on the borders of China, d. Another coffin. (Giibel, 

 ' Schw.,' 60, 407.) e. Old bell at Rouen, known by the name of Cloche 

 d' Argent. (Gerardin, 'Ann. Chin. Phys.,' 50,205.) /. Chinese yoxy. 

 (Thomson, ' Ann. Phil.,' 2, 209.) g. Bronze springs for the Balistae, 

 according to Philo of Byzantium. A. Antique sword, found in the 

 environs of Abbeville. 



Bronze is slowly attacked by boiling hydrochloric acid, tin being 

 extracted, leaving copper containing a small quantity of tin. Nitric 

 acid dissolves it readily. 



BRONZE, Ital. bronzn ; Fr. bronze ; Gr. xoAicbs (chalcos) ; Lat. as, is 

 essentially a compound of copper and tin, which metals appear to have 

 been among the earliest known. Copper is not unfrequently found in 

 its metallic state, and fit for immediate use ; and tin, though not so 

 met with, often occurs near the surface, and its ore is easily reduced. 

 These metals, though neither of them possesses the hardness requisite 

 for making instruments either for domestic or warlike purposes, appear 

 to have been early found capable of hardening each other by combina- 

 tion ; the bronze, which is the result of this combination, consisting of 

 different proportions of them, according to the purposes to which it is 

 to be applied. 



