586 TABLE YIT. Emissivity for Heat of Polished and Blackened Copper Surfaces. Difference of Amount of Heat lost per second per square centimetre of the surface per degree of difference of temperatures. Ratio. Temperature. Polished Surface. Blackened Surface. 5 000178 000252 707 10 000186 000266 699 15 000193 000279 692 20 000201 000289 695 25 000207 000298 694 30 000212 000306 693 35 000217 000313 693 40 000220 000319 693 45 000223 000323 690 50 000225 000326 690 55 000226 000328 690 60 000226 000328 690 TABLE VIII. Thermal Conductivities. Substances. Conduc tivity. i: Authority. Copper 96 I trii Iron 20 Do Air -"i . Oxygen. .. iClausius and Max Nitrogen f 0-000049 well, according to Carbonic oxide J kinetic theory. Carbonic acid 0-000038 Do do. Hydrogen 0-00034 Do. do. Stone, porphyritic trachyte... Underground strata 00590 0-005 (Ayrton and Perry, Phil. Mag., 187 8, first half-year, p. 241. ( Forbes and Wm. Sandstone of Craigleith ) Quarry 0-01068 { Thomson. Do. do. Traprock of Calton Hill Sand of Experimental Garden Water 0-00415 0-00262 0-002 Do. do. Do. do. J. T. Bottomley. Fir, across fibres 00026 iPeclet, in Everett s Units and Physi , , along fibres . -00047 cal Constants. Do. do. Walnut, across fibres ,, along fibres - Oak, across fibres 00029 00048 00059 Do. do. Do. do. Do. do. Cork 000029 Do. do. Hempen cloth, new old... 0-000144 0-000119 Do. do. Do. do. Writing paper, white Grey paper, unsized... . Calico (new), of all densities.. Wool (carded), of all den- ) sities 0-000119 0-000094 0-000139 0-000122 Do. do. Do. do. Do. do. Do. do. Finely carded cotton wool .... Eider down 0-000111 0-000108 Do. do. Do. do. TABLE IX. Diffusixities (Thermal, Material, and Electric). Substance. Thermal Conductivity.
- .
Thermal Capacity of Unit Bulk, c. Diffusivity. i/C. Authority. Copper 0-90 0-20 V 0-0000049 J 0-000038 0-00034 I 0-005 0-0005 0-002 0-84B 0-873 0-000307 0-000428 0-000307 0-5 39 1-00 1-18 0-22 0-16 0-088 8 1-12 o-oi 0-0013 0-002 2 Angstrom. Do. and Tait. Clausius and Maxwell, ) according to kinetic theory. ( Forbes and W.Thomson. J. T. Bottomley Iron Air Carbonic oxide. Carbonic acid ... Hydrogen Underground strata (rough average) Wood Water., Substance. Thermal Thermal Capacity Conductivity. of Unit Bulk. k. c. Diffusivity. Authority. t/c. Traprock o Calton Hill .. Sand of Expcri mental Gar den. Sandstone o Craigleith Quarry I 0-00410 I 0-00262 ) y O-OIOGS ies. 0283 3006 4623 0-5738 0-007 86 0-008 72 0-02311 0-01249 0-001 028 0-000011 6 O OOO 003 60 O OOO 000 54 0-000 000 73 1 0-000 003 6
- 0-000 008 85
0-0000106 0-000 020 2 000 012 7 000013 1 000 013 000 009 26 000 006 94 000 008 68 000 012 000 009 95 000 009 26 00000972 000 006 94 000 004 63 000 007 64 000 009 26 000 009 26 000 008 10 000 007 87 000 004 98 000 002 43 000 002 31 000 003 24 0-142 3 0* e >~>~t 0-7214 0-140 9 0-140 6 0-1586 0-098 3 0-480 0-180 2 0-6422 Forbes and W.Thomson. Everett. , Units and } 1 hw. C tn- ( ftaiitf,>.Vn. f Ayrton and 1 Perry, I Ml.
Mag., 1878,
first half- { year, p. 241. Fick. Volt. Prof. Mac i of Prague. Imperial Academy " of Sciences of Vienna, January 13, 1879. T. Schnh- meister, Wiener Sitzungs- berichte, April 3, 1879. Loschmidt, Imperial Academy of Vienna,! Oth - March 1870, quoted from art. DIFFU SION, vol.vii. P. 216. Gravel of Greenwich Observatory Hill f I terial rough ugh A i wat
- h wa
ugh v ion sa d, tin de, 1C de, e, nate, ite, ride, c, late, d air 1 hyd rogen a oxy d carl 1 mar 1 nifr ind h onic e nd hy 0090 JDiffusiri water Stone, porphy ritic trachyte. Ma Common salt, tl Cane sugar, thrc Caramel, throng Albumen, throw Cane sugar, thrc Water and comn Do. Hydrochloric aci Potassium chlor Potassium brom Potassium iodid< Potassium nitrat Potassium carbo Potassium sulph Ammonium chlo Sodium bromide Sodium iodide, Sodium chloride, Sodium nitrate, Sodium carbona Sodium sulphate Lithium bromide Lithium iodide, Lithium chloride Calcium chloride Cupric chloride, Copper sulphate, Zinc sulphate, Magnesium sulp Carbonic acid an Carbonic acid an Oxygen and hyd Carbonic acid an Carbonic acid an Carbonic acid an Carbonic acid an Sulphurous acid Dxygen and cart Carbonic oxide a er at 10 < ter at 13 ater at 9 It, throuf do. ough wat % soluti< i C .... c h water at 5 C. ... at 9C m through water... rogen ren onic ox it sh gas ... e HIS oxide drogen xide .. Irogen Electric Diffusivities. Name of Cable. Resistance per Nautical Milo in Ohms. 1 Reciprocal of the Resistance per Centimetre of length in electro- . magnetic C.G.S. Measure, i. Electrostatic Capacity per Nautical Mile in Microfarads. 2 Electrostatic Capacity per Centimetre of length in electro magnetic C.G.S. Measure. c. Diffusivity. t/c. 1 The ohm, or British Association unit of resistance, is equal to 10 7 electro-magnetic C.G.S, units. " One microfarad is one-millionth of the farad or British Association unit of electrostatic capacity, and is equal to 10- s electro-magnetic C.G.S. units of capacity. Suez-Aden ...... Aden-Bombay. . . Persian Gulf ) Cable, 1864 } Atlantic, 1865... French Atlan-) tic, 1869 ...(" Direct United^ States Cable) 10-42 7-02 6-25 4-27 3-16 2-88 0000178 0000264 0000296 0000434 0000086 0000643 0-3080 0-3610 0-3486 0-3535 0-4295 0-4095 1-93x10-21 1-95x10-21 1-88x10-2: 1-908x10-21 2-232x10-21 2-211x10-21 0-920x1016 1-304 xlOi 6 1-575x1016 2-274x1016 2-528 xlO 16 2-909 XlQi 1 This result has been accidentally printed 00000116 in some impressions of vol. vii. p. 217. TABLE X. Relative Diffusivlties of different Substances through Water. Approximate times of equal diffusion of different substances. Authority. 1 , Chloride of sodium 2-33 I Sulphate of Magnesia r: 1 >Graham. 49 1 Caramel
98
