Tasie VIJ.—Observed Indices of Refraction. 
Media of each observer arranged in the order of agreement with 
the exponential law, 
I, Fraunhofer’s Observations. 
Media ......... HB. | KC, F—), 
Crown-glass No. 9 .../1°525832/1°526849|1°529587|1°533005|1° nsg6acel- "54.1657|1°546566 
BMBREE NG.) 2 oo. cee. 1°330977|1°331709/1°333577|1° 335849 1°337788 1°341261|1°344162 
Crown-glass M ...... 1°554774|1°555930\1°559075/1°563 150|1°566741 1°573535|1°579470 
Solution of potash .../1"399629|1°400515/1°402805]1°405632| 1-408082/1°412579 1°416368 
Crown-glass No. 13...)1°524312|1°525299|1°527982/1°531372 1°5 34337) 1°539908)/ 17544684 
Water, No. 1 -»:,..00- 1°330938|1°331712/1°333577/1°335849|1°337818 1°341293|1°344177 
Oil of turpentine....../1°470496)1°471530|1°474434|1°478353|1°481736|1°488198 1°493874 
Flint-glass No. 13. .../1°627751/1°62968 1) 1°635036|1°642024|1°648260'1°66028 5| 1°67 1062 
Plint-glass No. 30 ...|1°623570|1°625477|1°630585/1°637356|1°64.3466| 1°655406|1°666072 
Flint-glass No.23 (2)..)1°626564|1°628451| 1°63 3666|1°640544|1°646780|1°6538849 1°669680 
Flint-glass No. 3...... 1°602042|1°603800) 1°608494/1°614.532|1°620042| 1'630772) 1°640373 
Flint-glass No. 23(1)..|1°626 596) 1°628469) 1°63 3667|1°640495|1°646756|1°658848| 1°669686 
ua OF BR, Gq, PH, 
II. Rudberg’s Observations. 
Topaz, 2nd axis ...... 160g4. |1°6093 «|1°6116 |1°6145 [16170 |1°6215 | 1°6254 
Quartz ex. ray ...... 1°5499 |1°5508 |1°5533 |1°5563 [175589 1175636 |1°5677 
Arragonite, 1st axis.../1°5275 |1°5282 1°5301 |1°5326 |1°534g |1°5388 |1°5422 
Quartz O, ray .,..06...{1°5409 175418 [175442 {175471 {1°5496 [175542 | 175582 
Topaz, 3rd axis .,.... 16105 j1°6114 «|1°6137 «| 16167 [16191 |1°6236 |1°6274 
Calc-spar O. ray ...... 16531 |1'6545 |1°6585 |1°6636 |1°6680 |1°6762- |1°6833 
Topaz, 1st axis .,....|1°6179 |1°6188 [16211 |1°6241 |1°6265 {176312 © |1°6351 
Arragonite, 3rd axis..)1°6763 |1°6778 |1°6816 |1°6863 [16905 © [1°6984 | 177051 
Cale-spar ex. ray...... 14839 |1°4845 [1°4863 |1°4887 |1°4907 |1'4945 |1°4978 
Arragonite, 2nd axis ..|1"6806 /1°6820 /1°6859 |1°6908 |1°6951 |1°7032 | 1701 
III. Powell’s Observations. 
Sulphate of magnesia.|1°3434 |1°3442 |1°3462 |1°3486 |1°3504 |1°3540 |1°3570 
Oil of anise, T. 20°*9..|1°5451 |1°5473  |1°5534 [175623 |1°5707 |1°5881 |1°6053 
Oil of anise, T.13°25../1°5482 [175504 |1°5565 |1°5650 |1°5733 |1°5g01 176066 
Sol. of potash, T.16°..]1'4024 |1"4036 14061 |1°gogx |1°4117 |1°4162 |1°4.199 
Sulphate of soda.,,.... 1°3392 |1°3398 |1°3419 |1°3442 |1°3462 |1°3499 [13528 
Nitrate of lead ...... 1°3455 |1°346r |1°3482 |1°3506 [1°3528 {173568 |1°3600 
Superacetate of lead..|1°3429 |1°3437 |1°3455 |1°3480 |1°3498 |1°3538 [173571 
Nitrate of bismuth .../1°3306 [1°3315 |1°3332 |1°3355 |1°3374 «|1°3410  |1°3437 
Nitric acid ..........5- 13988 |1°3998 |1'4026 |1°4062 |1'4092 |1'4155 [1°4206 
Subacetate of lead ...|1°3350 [1°3357 |1°3373  |1°3398 |1°3417 |1°3453 |1°3481 
Oil of sassafras ...... 1°§257 |1°5275 |1°532x |1°5387 |1°5448 |1°5575 |1°5693 
Alcohol ....,.+.. sveeee/1°3628  [1°3633 0 |1°3654  [1°3675 | 1°3696 = |1°3733 17376 
Muriate of lime ...... 14006 |1°4016 |1"4go40 |1°4070 |1"4099 |1°4150 |1°4190 
Muriate of ammonia..|1°3499 |1°3508 |1°3529 |1°3552 |1°3575 |1°3617 |1°3650 
Oil of anise, T.15°r..)1°5486 |1°5508 |1°5572 |1°5659 |1°5743 |1°5912 | 1°6084 
Muriatic acid ......... 14050 |1'4060 |1'4095 |1°4130 |1°4160 |1°4217 |1'4261 
Sulphuric acid ...... 14321 |1°4329 |1°4351 |1°4380 |1°4400 |1°4440 |1°4463 
Rock-salt.......2,.0»2+ 1°5403 |1°5415 [15448 |1°5498 |x°S5q4r |1°5622 |1°5691 
Nitrate of mercury ...|1°3408 |1°3419 © [1°3439 |1°3462 |1°3487 [173528 |1°3560 
ICLEOSOLE ...0020025.000- 1°5320 |1°5335 |1°5383 |1°5452 |1°5515 [175639 1175749 
Pyroligneous acid .../1°3729 |1°3745 |1°3760 |1°3785 |1°3807 |1°3848 |1°3884 
Bisulphide of carbon..|1°6182 |1°6219 |1°6308 {176438 |1°6555 |1°6799 |1°7020 
Water, T. 15°°8 ....,. 1°3317 |1°3326 11°3343 |1°3364 [1°3386 |1°3429 |1°3448 
Oil of cassia, T. 14°.../1°5945 |1°5979 |1°6073 |1°6207 |1°6358 |1°6671 = |1°7025 
Solution of soda..,.... 14036 |1°4039 |1°4075 |1°4109 |1°4134 |1°4181 |1°4221 
Muriate of baryta ...|1°3398 |1°3406 |1°3421 |1°3438 [173466 = |1°3504 |1°3531 
Nitrate of potash...... 13457 |1°3468 |1°3487 9 |1°3510 |1°3533 |1°3586  |1°3608 
reve a gol 15895 |1°5930 |1°6026 |1°6174 |1°6314 | 16625 |1°6985 
Oil of cassia, T. 10°. -|2'5963 16007 |1°6104 |1°6249 = |1°6389 |1°6698 = | 1°7039 
2C2 
