ON THE THERMAL CONDUCTIVITIES OF CERTAIN ROCKS:. 



143 



Effect of pressure and temperature on conductivity practically nil. Effect of 

 discontinuity to lessen conductivity, but not to any great extent where good 

 contacts exist between discontinuous portions. Effect of moisture largely to 

 increase conductivity, attaining a maximum before saturation of the rock is 

 reached, 



Calvert and Johnson, 'Ph. Trans.' 1858, 349, and 18.59, 831.— Metals, alloys, and 

 amalgams. Square bars, with one end immersed in hot, other in cold, water, 

 both of known temperature. Means taken to obviate passage of heat between 

 calorimeters, except through bar, and rise of temjaerature of cold water in given 

 time noted. Relative results only, and probably only order of conductivity since 

 inrtuence of sp. heat must have been considerable. Long table of resulting 

 figures. Action of compound bars compared with that of alloys. 



Guthrie, ib. 1869, 637.— Liquids. Same apparatus as in ' Ph. Mag.' 4, 35, 283, but 

 modified by having cone surfaces of Pt, ground quite plane, and with an arrange- 

 ment for regulating and measuring distance between. Figures for relative 

 ' resistances ' given. No. of ht.-units arrested per minute by 1 sq. dm., 1 mm. 

 thick, T (of air) being 20°-17 C. and A T 10° C, as follows :~ 



Water . 

 Glycerine 

 Acetic «cid . 

 Acetone 

 Ethyl oxalate 

 Sperm oil 

 Alcohol . 

 Ethyl acetate 

 Nitrobenzol . 

 Amyl oxalate 

 Butyl alcohol 



•0106 

 •0407 

 •0888 

 •0902 

 •0938 

 •0938 

 •0963 

 •0963 

 •1045 

 •1060 

 •1060 



Amyl acetate 

 Amylamine . 

 Amyl alcohol 

 Oil of turijentine . 

 Butyl nitrate 

 Chloroform . 

 Bichloride of carbon 

 Mercury amyl 

 Ethylene dibromide 

 Amyl iodide . 

 Ethyl iodide . 



•1060 

 •1075 

 •1084 

 •1245 

 •1258 

 •1283 

 •1369 

 •1369 

 •1395 

 •1407 

 •1505 



Thomson, W. ' Camb. Math. Journ.' 3, 25. — Motion of heat in a sphere. 3, 71. Motion 

 of heat in homogeneous solids. 3, 171. Linear motion of heat. 3, 206. Ditto 

 part 2. 4, 33. Equations of motion of heat refciTed to curvilinear co-ordinates. 

 4, 67: Some points in the theory of heat. 4, 179. Orthogonal isothermal surfaces. 



Stefan, ' Chem. Soc. Jour.,' 25,591 (1872). — Gases: Abstract of method. Eesults 

 for air K = -OOdOSe (c.g.s.) Conducting power of a gas independent of density. 

 K for hydrogen = seven times K for air. 



Mayer, ' Sill. Amer. Jour.' (3) 4, 37 (1872) Cf. ' Ph. Mag.' (4), 44, 257. 



Forbes, ' P.E.S.E.' 1, 5 (1833).— Conducting powers of metals for heat and electricity. 

 Order for heat determined by Fourier's contact-thermometer : Au Ag Cu Brass 

 Fe, Zn, Pt, Sn, Pb, Sb, Bi. o » . 



Forbes, ib. 1, 223 (1838). — Results of observation of underground thermometers; and 

 ib. 1, 343 (1841).— Same discussion continued. Order of conductivity. Sand- 

 stone, sand, trap, beginning with the best. 



Forbes, ' P.R.S.E.' 4, 607 (1862). Conductivity of Fe. Loss of heat at different tem- 

 peratures by radiation and convection determined directly. Conductivity then 

 calculated for different temperatures ; approximate results, K = (c g s ) 0° 206 • 

 50°, ^186 ; 100°, ^166 ; 150°, -1455 ; 200°, •127. v t. ^ . 



Ib. 5, 369 (1865).— Further reductions and observations with the same bars, 

 and also with another of different make. 



1862 



1865 



1865 

 (new bar) 

 •153 

 •1395 

 •129 

 •123 

 •118 

 ■114 



Tait, ib. 8, 55 (1873).— Note on Angstrom's method of determining conductivity, with 

 some approximate determinations. 



