222 
PROFESSOR POWELL ON A NEW CASE OF 
(34.) Glass and Oil of Sassafras, r='04 inch. 
Ray. 
f^p- 
f^tn* 
X 
Diff. = n. 
Remarks. 
B. 
1-526 
1-526 
0 
0 
0 
D. 
1-529 
1-532 
— -003 
— 138 
— 5-5 
- 5 
F. 
1-536 
1-545 
-•009 
— 501 
-20 
-15 
Hence in this case 
G. 
1-542 
1-557 
— -015 
- 945 
-37-8 
— 18 
arrangement I. will 
H. 
1-546 
1-569 
— -023 
— 1571 
-62-8 
-25 
give bands. 
65 
(35.) Glass and Oil of Cassia (Report, No. ii.), r 
= •015 inch. 
B. 
1-526 
1-594 
--068 
— 2676 
- 40 
D. 
1-529 
1-607 
— -078 
— 3586 
— 54 
— 14 
F. 
1-536 
1-636 
— -100 
— 5574 
— 84 
— 30 
Here arrangement 
I. will give bands. 
G. 
H. 
1-542 
1-546 
1-667 
1-702 
— •125 
—•156 
- 7867 
-10656 
— 118 
— 160 
~ 34 
42 
—120 
(36.) Glass and Oil of Cummin, 
r=*04 inch. 
B. 
1-526 
1-502 
+ •024 
+ 944 
+ 37-7 
D. 
1-529 
1-507 
+ •022 
+ 1011 
+ 40-4 
+ 2 
E. 
1-533 
1-513 
+ •020 
+ 1028 
+ 40-8 
+ 1 
Here arrangement 
II. would give bands 
F. 
1-536 
1-520 
+ •016 
+ 891 
+ 35 
- 6 
from B. to E, and 
G. 
1-542 
1-533 
+ •009 
+ 567 
+ 22^6 
— 12 
arrangement I. from 
H. 
1-546 
1-543 
+ •003 
+ 205 
+ 8 
— 14 
E to H. 
-32 
( 37 .) We may remark that the indices for oil of cummin are all open to some un- 
certainty*, and it is easily found that a change in the indices of D and E of -001 only 
would give no hands between B and E with either arrangement ; for we should have on 
this supposition — 
Ray. 
f^P- 
X 
Difr.=»i. 
Remarks. 
B. 
D. 
1-508 
+ •021 
+ 564 
+ 37-7 
+ 38-5 
0 
No bands. 
E. 
1-514 
+ •019 
+ 976 
+ 38-8 
0 
(38.) Glass and Oil of Turpentine. 
t = -04 inch. 
B. 
D. 
1-526 
1-529 
1-470 
1-474 
+ •056 
+ •055 
+ 2203 
+ 2528 
+ 88 
+ 101 
+ 13 
F. 
1-536 
1-482 
+ •054 
+ 3009 
+ 120 
+ 19 
Hence arrangement 
G. 
1-542 
1-488 
+ •054 
+ 3402 
+ 136 
+ 16 
II. will give bands, 
H. 
1-546 
1-494 
+ •053 
+ 3619 
+ 145 
+ 9 
+ 57 
* See Report, British Association, 1839, p. 12. 
