28 M. MELLONI ON THE FREE TRANSMISSION 
the heat, the lamp was brought nearer and nearer until we obtained, 
through the combination 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°. 
Tas e Il.—Glass (uncoloured). Common thickness 1™™88. 
Deviations of Rays 
the galvanometer. transmitted. 
No screen . EEpospeies 30°00 100 
Flint-glass i Guinand) .. ee 22°90 67 
Flint-glass (English) © ...............ee00e 22°43 65 
Flint-glass apne theds ween Grlnaen. re 22°36 64 
Mnother Kind. 2. casans sesnisens <nashmwsineycs 22:19 64 
BEPC OE IANS 508 a adn's dopa anicin ssengenanace 21°89 62 
REPT MATME et a rheracs a o5.0 dais s Ssuiaindonas eae eion 21°10 60 
PRREEMICE MATL 52h Urpays soe eves eoseas snigace 20°78 59 
Crown-glass (French) ... es are 20°58 58 
Window-glass (common)... MES 19°25 54: 
mnbhenleiind  ee iis. cdh haces teaeiuesheseed 18°56 52 
PEBDINOT KANG) a sstegeiens oadeiuiad aapdsy sedans 17°83 50 
Crown-glass (English) ...,.........0.seseee 17-22 49 
TaBLeE Il.—Ziquids... Common thickness 9™™-2], 
Deviations of Rays | 
the galvanometer. transmitted. 
Winrar ans 1S Jeanreeadeew tee tecswasncievolee= 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 ol 
Nuiceil (yellow) Persea veseenens 11-10 31 
Essence of turpentine (colourless) ...... 10°83 31 
Essence of rosemary (colourless),........ 10°46 30 
Oil of colza (yellow) snips stadia 10°38 30 
Oil of olives CaaS yellow) esigsncicck 10°35 30 
Naphtha (natural—a light brown yellow) O77 28 
Balsam of copaiba (a sufficiently decided 
brown yellow) <...2:... See 9°39 26 
Essence of lavender (colourless)......... 9°28 26 
Oil of pink [huile deillet] (very slightly 
yellowish) ... shsninet 9°26 26 
Naphtha (rectified, colourless) sgeiatanian 9:10 26 
Sulphuric ether (colourless) ...........- 7:59 21 
Pure sulphuric acid (colourless) ... “fi ad 6°15 17 
Sulphuric acid (of Nordhausen, of a suf- ; 
ficiently decided brown) ............+. 6:09 17 
Hydrate of ammonia (colourless) Pre F 547 ig abeed: 
