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30
INDEX OF REFRACTION OF SULPHUR
The following are the readings in degrees for the first six sets of observations with P (a, b) or Q (c. d).
| P. | |||||||||
| a. | b. | Mean. | Difference. | ||||||
|---|---|---|---|---|---|---|---|---|---|
| 1.......... | 216 | 144 | 188 | ||||||
| 71 | |||||||||
| 2.......... | 144 | 74 | 109 | ||||||
| 70 | |||||||||
| 3.......... | 74 | 4 | 39 | ||||||
| 70 | .5 | ||||||||
| 4.......... | (360 | )+4 | 293 | 328 | ·5 | ||||
| 70 | ·5 | ||||||||
| 5.......... | 293 | 223 | 258 | ||||||
| 70 | ·5 | ||||||||
| 6.......... | 223 | 152 | 187 | ·5 | |||||
| 352 | ·5 | .... A. | |||||||
| Q. | |||||||||
| c. | d. | Mean. | Difference. | ||||||
| 1.......... | 308 | 360 | +18 | 343 | |||||
| 70 | |||||||||
| 2.......... | 18 | 88 | 53 | ||||||
| 70 | |||||||||
| 3.......... | 88 | 158 | 123 | ||||||
| 71 | |||||||||
| 4.......... | 158 | 230 | 194 | ||||||
| 71 | |||||||||
| 5.......... | 230 | 300 | 265 | ||||||
| 70 | |||||||||
| 6.......... | 300 | 360 | +10 | 335 | |||||
| 352 | ·0 | .... B. | |||||||
Mean of A–B = 352·25.
.
From the results given above it would appear that the index of refraction of sulphur is very near 1.734.
The method is also well suited for liquids; no large quantity of material is required; and the results possess a high degree of accuracy.
The determination of the indices of other solids and liquids are in progress. An account of these will be given in a future communication.
(Proc. Roy. Soc., Oct. 1895.)
