•28 M- MELLONI ON THE FREE TRANSMISSION 



the heat, the lamp was brought nearer and nearer until we obtained, 

 through the couibiuation of the three plates, the same indication of 19° 

 that was furnished by the thick glass when exposed singly to the radia- 

 tion of 30°. 



Table I. — Glass (uncoloured). Common thickness r"™-88. 



Deviations of Rays 

 the galvanometer, transmitted. 



No screen 30-00 100 



Flint-glass (of Guinand) 22-90 67 



Flint-glass (English) 22-4.3 65 



Flint-glass (French) 22-36 64 



Another kind 22-19 64- 



Mirror-glass 21-89 62 



Another kind 21-10 60 



Another kind 20-78 59 



Crown-glass (French) 20'58 58 



Window-glass (common) 19-25 54 



Another kind 18-56 52 



Another kind 17-83 50 



Crown-glass (English) 17-22 49 



Table II. — Liquids. Common thickness 9°""*21. 



Deviations of Rays 

 the galvanometer, transmitted. 



Mirror-glass 19*10 53 



Carburet of sulphur (colourless) 21*96 63 



Chloride of sulphur (of a strong brown- 

 ish red colour) 21-83 63 



Protochloride of phosphorus ^colourless^ 21-80 62 



Hydrocarburet of chlorine (colourless) 13-27 37 



Nut-oil (yellow) IMO 31 



Essence of turpentine (colourless) 10*83 31 



Essence of rosemary (colourless) 1 0-46 30 



Oil of colza (yellow) 10-38 30 



Oil of olives (greenish yellow) 1 0-35 30 



Naphtha (natural — a light brown yellow) 9-77 28 

 Balsam of copaiba (a sufficiently decided 



brown yeUow) 9-39 26 



Essence of lavender (colourless) 9-28 26 



Oil of pink [Az«7e d'ceillet] (very slightly 



yellowish) 9-26 26 



Naphtha (rectified, colourless) 9*10 26 



Sulphuric aether (colourless) 7*59 21 



Pure sulphuric acid (colourless) 6-15 17 



Sulphuric acid (of Nordhausen, of a suf- 

 ficiently decided brown) 6-09 17 



HycU-ate of ammonia (colourless) 5-47 15 



