uncertainty- these metals were employed as compressed powders. The cubical expansion of mercury from-o° to 1009 C. is -018153 =5 IGH (Regnault) (See THERMOMETRY.) Fhtsibility and Volatil-ity.-T-The fusibility in different metals is very different, as shown by the following table, which, besides including all the fusing points (in degrees C.) of metals which have been determined numerically, indicates those of a selection of other metals by the positions assigned to them in the table. Name of Metal. ' Specific Gravity. Barium ~ ', 3-75 Zirconium, , 4-X5 Vanadium, powder 5-5 Gallium ' 5-95 Lanthanum 6463 Cerium 6-68 Antimony 6-62 V Chromium 6-50 Zinc, ingot 6-915 roller wut .. . 7-2 Manganese ~ ..... 7-39 » Tin, cast ~ ' ... .. 7-29 to -7-299crystallized by electrolysis from solutions 7- 178 Indium . ... ..; 7-42 Iron, chemically pure, ingot . ... 7-844 thin sheet 7-6 wrought, high quality 7-8 to 7-9 Nickel, ingot .. ' A 8-279 ' » forged .. . =' -8-666 Cadmium, ingot . . '8-546 hammered .... 8-667 Cobalt . . ..... 8-6 Molybdenum, containing 4 to 5 % of carbon 8-6 Copper, native ' .. .... 8-94 Cast . ... . -8-92 wire or thin sheet 8-94 to 8-95 electrotype, pure 8-945 Bismuth . 9-823 at I2° Silver, cast . . 10-4 to 10-5 stamped . . 10-57'-Lead, very slowly frozen .. . I 1-254quickly frozen in cold water 1 1 -363 Palladium ... . 1 1 -4 at 22-5° Thallium ' II~86 Rhodium 12-1-Rutheniurn 12-26 at 0-° Mercury, liquid .. . 13-595 at 0° solid - .. . 14-39 below-40° Tungsten, compact, by Hg from chloride 2 16vapour T54 as reduced by hydrogen, powder 19-13 Q-Uranium 18-7 Gold, ingot . . 19-265 at -13° stamped . . powder, precipitated by ferrous sul- E phate .. . .. 19'3l to I9'34 I9~55 to I'9~72 Name of Metal. Melting Point. Boiling Point. Mercury - ' "38'8 357-Caesium 26'27 3 Gallium 30- I Rubidium 38-5 Potassium 62-5 7 1 9-73 1 Sodium 95-6 861-954 Iridium 155-Lithium 180°0 V » Tin 231-9 1450-1600 Bismuth 269-2 IO90°145O-Thallium 290 Cadmium 320-7 780 Lead ' 327-7 1450-1600 Zine .... 419 ~ 929-954 I nczpaent red heat 525-Antimony 629-5 - Magnesium 632-6 about 1100 Aluminium 655 Cherry redheat 700 -Calcium 780-Lanthanum 810 Ba;-ium 850 Silver 962 Gold 1064 C ofper I O82 2 100 Ye low heat 1 100 Iron 1300-1400 Nickel 4 1427 Cobalt 1800, (?) Daizling white heat 1500-1600 Palladium 1 500, Platinum 1 760 Rhodium above -Pt. Iridium , , 12200 Ruthenium, 'Ir Tantalum In eIec'tric Osmium furnace - Platinum, pure ' » . QI-50/ lridium 22-2 Osmium 22-477 Thermal Properties.-The specific heats of most metals' have been determined. The general result is that, conform ably with Dulong and Petit's law, the “atomic heats” all come to very nearly the same value (of about 6~4); i e atomic weight by specific 'heat #6-4. Thus we have for silver by theory 6'4/108='0593, and by experiment -o570 for 10° to 100° C. The expansion by heat varies greatly. The following table gives the linear expansions from 0° to 100° C. according to Fizeau (Comptes rendus, lxviii. 1125), the length at 0° being taken as unityt '— Expansion-Name of Metal. os to 100° Platinum, cast . -000 907 Gold, Cast . -001 451 Silver, cast 'OOI 936 Copper, native, from Lake Superior A -ooi 708 artificial . . . -001 86g Iron, soft, as used for electromagnets -001 228 reduced by hydrogen and compressed -001 208 Cast steel, English annealed -001 1 IO Bismuth, in the direction of the axis °OOI 642 at right angles to axis °OOI 239 mean expansion, calculated -001 374 Tin, of Malacca, compressed powder -002 269 Lead, cast . . -002 948 Zinc, distilled, com ressed powder -002 905 Cadmium, distilled? compressed powder -003 102 Aluminium, cast .. . -002 336 Brass (71 -5 % copper. 28-5 % zinc) ~0OI 879 Bronze (86-3 % copper, 9-7 % tin, 4-0 % zinc) -001 802 The coefficient of expansion is constant for such metalsvonly as crystallize in the regular system; the others expand differently in the directions of, the different axes. To'eliminate this source of f SPOT practical purposes the volatility of metals may be stated as 0 ows:- » 1. Distillable below redness: mercury. 2. Distillable at red heats: cadmium, alkali metals, zinc, magnesium.

3, Volatilized more or less readily when heated beyond their fusing points in open crucibles: antimony (very readily), lead, bismuth, tin, silver; V 4. Barely so: gold, '(copper), 5. Practically non-volatile: (copper), iron, nickel, cobalt, aluminium; also lithium, barium, strontium and calcium. -In the oxyhydrogen flame silver boils, forming a blue vapour, while platinum volatilizes slowly, and osmium, though in fusible, very readily. Latent Heats of Liquefaction.-Of these we know little(The following numbers are due to Person-ice, it may be stated, being 80. Name of Metal. Lggf Name of Metal. Léiggft Mercury 2-82 Cadmium - I3-6 Lead 5-37 Silver 21-1 Bismuth . 12-4 Zinc 28-1, The latent heat of vaporization of mercury was found by Marignac to be 103 to 106.1 Conductivfily.-Conductivity, whether thermic or electric, is very differently developed in different metals; and, as an exact knowledge of these' conductivities is of great importance, much attention has been given to their numerical determination (see CoNDUc'r1oN, ELECTRIC; and CONDUCTION or HEAT). The following table gives the electric conductivities of a number of metals as determined by Matthiesen, and the relative'inte'rnal thermal conductivities of (nominally) the same metals as determined by Wiedemann and Franz, with rods about 5 mm. thick, of which one end was kept at IOO° C., the rest of the rod in a “ vacuum ” (of 5 mm. tension) at 12° C. Matthiesenls results, except in the two cases noted, are from his memoir in Pogg Ann., 1858, ciii., 428

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