126 NEWNES PRACTICAL MECHANICS December, 1939 greenish -yellow appearance. In English cent. ; tin, 2.5 per cent. ; , 7.1 per cent. per alloys recently introduced in America. standard gold the silver is replaced by Sometimes about .5per cent. of alu- Typical composition :silver,70.44 per copper. minium is also added. cent.; copper, 28.90 per cent. ; beryllium, Autogenous Soldering. -The uniting of twoBearings Metals. -See Anti -friction Metals. .87 per cent. Used as a resistance -wire pieces of metal together simply by meltingBell Metal. -A type of bronze or copper -tin. material. their edges by means of a blowlamp or alloy containing from 12 to 24 per cent.BessemerSteel. -Steel manufactured by other source of heat. The word " auto- of tin.Technically known as Hard the Bessemer process (the invention of geneous " means " self -generated." Bronze." Sir Henry Bessemer in1856). In the The lead linings of chemical and acidBeryllium. -Formerly named " Gluoinum." Bessemer process, the molten " pig " iron tanks are usually autogenously soldered Metallic element. Chemical symbol, Be ; is run into a receptacle known as a because the presence of any dissimilar At. No. 4 ; At. Wt. 9 ; M.P. 962°C. ; Sp. " converter," in which a blast of air is metal at the joints would set up electro- Gray. 2.1; Sp. Ht. .397. passed through it.Impurities are thus lytic actions which might attain serious Chief ore :Beryl, 3BeO.A1203.6SiO2. burned out of the molten metal. proportions. Occurs also in gems, such as emerald. BibraAlloy. -Composition :Bismuth, 8 Avional.-A Swiss alloy. Com- Name of the metal derived from its parts; tin, 9 parts; lead, 38 to 40 parts. position :Copper, 4.75 ; , 0.5 ; principal ore, beryl.Beryllium was firstBidery Metal. -An alloy which was at one , 1.0 ;, 1.4 per cent. ; isolated in an impure form by F. Wohler time very popular in India.It was first remainderaluminium. Ishardand in 1827. Not prepared in a pure, state manufactured at Bider. near Hyberabad, enduring. Tensile strength about 30 until 1885, and until very recent times it in India, from which town it takes its tons/sq. in. has remained an uncommon metal. Now- name. The metal does not easily tarnish adays,however,berylliumisrapidly or oxidize, and was at one time employed B attaining a status of commercial import- for the manufacture of Indian cooking Babbit's Metal. -The original alloy recom- ance, as a light alloying metal, particu- vessels.Its composition (average)is : mended by Babbit was made up of the larly in America. Tin, 1.4 per cent ; copper, 11.4 per cent. ; followingingredients :copper,4lb. ; Beryllium is a white metal resembling zinc, 84.3 per cent.; lead, 2.9 per cent. antimony, 8 lb.; tin, 24 lb.To every magnesium in appearance but being con-Billet. -A short, thick metal bar which is pound of the above, 2 lb. more of tin was siderablylighterin weight.Next to used for or rolling. added. lithium, beryllium is the lightest metal Many softliningand anti -friction known.Itisfairlymalleable,andBimetal. -Name given to two dissimilar, bearing metals have subsequently borne remains unchanged in ordinary air, even metals sweated or fused together so as the name of " Babbit," but the above is when heated. Powdered beryllium, how- to make up a composite metal sheet. the originalalloy devised by Babbit ever, when heated, burns much in the Nowadays, bimetals are much used in himself. same manner as magnesium, emitting a consequence of the unequal ratesof Bahnmetall.-" Railway Metal."A soft brilliant light. expansion of their constituent metals, bearing metal used on the German State Beryllium is acted upon by mineral causing the bimetal to curl when heated Railways for the linings of axleboxes. acids and bears a close chemical resem- and thereby enablinga temperature - Was introduced during the Great War blance to magnesium. It has now become measurement to be made or an electrical and is still used with, it is said, excellent an important alloying metal, and it may circuit to be opened or closed at a definite results.It consists of lead alloyed with yet be employed in the pure state in view temperature. small amounts of sodium, calcium and of its extreme lightness, provided that itsBinary Alloy. -An alloy pontaining two lithium.Approximate composition : manufacture can be cheapened sufficiently. constituent metals. sodium, .58 to .62 per cent.; calcium,Beryllium -Cobalt -Copper. -A high -conduc-Binary Steels. -These are alloy steels con. .59 to .73 per cent. ;lithium, .04 per tivity copper alloy, not unlike beryllium., taming one special alloying metal, as, for cent. ; remainder lead.It has a hardness copper,butcontaining.4percent. instance, chromium steel. of about 34 Brinell, and a compressive beryllium, 2.6 per cent. cobalt, balanceBirmabright.-An aluminium -magnesium strength of between 25,000 and 30,000 copper. Has an average tensile strength alloycontainingabout 7 percent. lb. per sq. in. of 95,000 lb. per sq. in. magnesium (and sometimes 1 per cent. Banka Tin. -Tin from the Island of Banka,Beryllium Copper. -A copper - beryllium of manganese). Can he worked easily and in the Dutch East Indies. alloy containing from 1.5 to 2.75 per is resistant to atmospheric tarnishing and Barium.-Metallie element. Chemical sym- cent. of beryllium, the standard alloy corrosion. bol, Ba ; At. No. 56 ; At. Wt. 137 ; M.P. having aberylliumcontentof 2.25.BirmailsSpecialAlloy. -An aluminium 850°C.Sp. Gray. 3.75 ; S. Ht. .068. Sometimes up to .5 per cent. of nickel is alloy containing from 10 to 13 per cent. First prepared (in an impure form) by added to these alloys to restrict grain size of silicon and from 2.5 to 3.5 per cent. Davy in 1808.Its name is derived from during annealing. They were originally of nickel, in addition to small amounts the Greek, baron, heavy, in reference to investigated by Dr. G. Masing in 1926 of copper, iron and manganese.It has the heavy mineral " barote " (afterwards and are now of much commercial interest. a good resistance to corrosion and a called" baryta ") which contains the In the annealed condition, the stan- high tensile strength.It is tough and element. dard beryllium -copper alloy has a tensile ductile. Chiefores : Heavyspar,Barytes, strength of 70,000 lb. per sq. in., whilst byBkmidiuni.-An produced RaSO4, Witherite, BaCO3. Barium, when cold rolling and heat -treatment, its ten- in Birmingham. Hence its name. It has pure, is a silvery, lustrous metal, having sile strength can be still further increased. a composition and properties similar to ayellowtinge.Ithasrarelybeen The alloy is obtainable in rod, strip, sheet "Y" alloy, which see. obtained in the pure state,however, or cast form. It is now being much usedBirmingham Platinum. -A white brass of owing to the extreme difficulty of its forthe production of springs, which variable composition.The following is preparation.It tarnishes rapidly in air, show remarkable endurance properties, typical :copper, 43 per cent.; zinc, 57 becoming coated with a film of oxide.It and, also, for the making of non -sparking per cent.Also known as" Platinum decomposes water with the evolution of tools.With the gradual cheapening of hydrogen and the formation of barium metallic beryllium, beryllium copper Lead." This alloy was formerly used for hydroxide, Ba (011)2. alloys have a promising future. casting buttons. As a metal, barium has no uses what-Beryllium Gold. -Gold -beryllium alloys con-Bismuth Amalgam. -A thinly fluid amal- ever, although its chief ore, barytes, is of taining from .5 to 5 per cent. of beryllium gam prepared by adding 'mercury to great value in industry. Alloys of barium have been worked out in America. When molten bismuth. Almost any proportions with lead, aluminium, bismuth and anti- the beryllium content exceeds the former of these two ingredients may be used. mony have been reported from time to percentage, however, they become too Bismuth amalgams, on account of their time.Barium is closely related in chemi- brittle to work, the beryllium exerting fluidity are useful for filling very delicate cal properties to calcium and strontium. moulds.Other amalgams are also ren- an extreme hardening effect upon the dered more fluid by adding to them a Base Metals. -See Noble Metals. gold.Some of these alloys have been small proportion of a bismuth amalgam. Bath Metal. -An alloy which was at one used as gold solders and dental inlays. Bismuth amalgam is sometimes used time very popular in England for theBeryllium Silver. -An alloy of silver and forsilveringglass globes and similar manufacture of teapots, sugar basins and beryllium containing from .41 to .90 per articles. other tableware.It is silvery -white in cent. of beryllium. It has the remarkable Theamalgamwillpassthrough colour, and takes a high polish.Com- property of remaining untarnished in chamois -leather like mercury. The drops, position: copper 55 parts ; zinc 45 parts. atmospheres charged with sulphur com- however, are pear-shaped and not per- Baudoin'sAlloy. -Animitationsilver. pounds which would rapidly blacken pure fectly globular as in the case of pure Composition :copper,72percent.; silver. mercury. nickel,16.6 per cent. ;cobalt,1.8 perBermylliu-Silver-Copper.-A group of cop- (To be continued)