392 
Journal of Agricultural Research 
Vol. XXVI, No. 9 
dissolved in 250 cc. of petroleum ether. Two cc. of this solution of 
carotin were diluted to 100 cc. with U. S. P. ether and the transmittancy 
determined. The transmittancy is given in Table V and is determined 
from the graph; 41.9 mgm. of carotin were found in the solution, which 
contained 42.0 mgm. by weight. 
Table IV .—Comparison of the transmittancies of identical concentrations of carotin in 
petroleum ether, in alcohol, and in ether, using the mercury line 435. 8 
Solvent. 
Transmittancy. 
Percentage of 
petroleum ether 
in the solution. 
Carotin per 
liter.® 
Petroleum ether. 
O. 0246 
IOO 
Mgm. 
4. 20 
O. 0252 
IOO 
4. 20 
O. 0632 
IOO 
3 * 15 
O. 1570 
IOO 
2 . 10 
O. 1570 
IOO 
2 . 10 
O. 3910 
IOO 
I. 05 
Absolute ethyl alcohol. 
O. 0263 
5.000 
4. 200 
O. 0612 
3 * 750 
3 - IS° 
O. 1530 
2. 500 
2 . IOO 
0.1580 
2. 500 
2 . IOO 
O. 3960 
1.250 
I. 050 
O. 6220 
0. 625 
0.525 
U. S. P. ether. 
0. 0228 
5.000 
4. 200 
0.0546 
3 - 75 ° 
3 * 150 
0.1430 
2. 500 
2 . IOO 
0.3690 
1.250 
I. 050 
0.5890 
O. 625 
0. 525 
0.0235 
5. OO 
4. 20 
0.1460 
2. 50 
2 . IO 
0.3730 
1-25 
I. 05 
a The carotin used to obtain the measurements in this table was pure. 
Table V .—Amount of carotin determined spectrophotometrically in a solution which 
contained 42.0 mgm. per liter by weight 
Scale. 
Transmit¬ 
tancy. 
Dilution. 
Milligrams 
of carotin 
found per 
liter. 
43 S -8 
0. 0464 
12 . 5 X 
41.9 
The specific transmissive index for carotin in petroleum ether, alcohol 
or ether can then be calculated from the data obtained from the graphs 
in Figure 3, using the equation— 
k — 
l°glO T 
be 
The average value for k , the specific transmissive index (extinction 
coefiicient) for carotin in petroleum ether or alcohol for the mercury 
line 435.8 is found to be 1.915, while that for ether is found to be 1.990. 
