Mar. 1,1925 
Physical and Chemical Properties of Carotin 
471 
These solutions were stored in the ice 
box and from time to time the trans- 
mittancy was determined spectropho- 
tometrically. Dilution was often found 
necessary, because the instrument is 
best adapted for use with carotin 
solutions of low concentration. 
In Table IV are presented results 
obtained with solutions of carotin in 
alcohol, in ether, and in petroleum 
ether, when kept for varying lengths 
of time. 
Table IV.— Spectrophotometric determi¬ 
nations showing the stability of carotin 
in alcohol , in ether , and in petroleum 
ether when stored in the ice box for 
varying lengths of time 
Num¬ 
ber of 
days 
Trans- 
mit- 
tancy 
Solution 
Dilu¬ 
tion 
1 
Caro¬ 
tin per 
liter 
0. 0403 
Absolute alcohol. 
1 
Times 
XI ! 
Mgm. 
3. 64 
0 
- .1360 
Absolute ether... 
X20 
43. 60 
.0976 
Petroleum ether.. 
X20 
50. 80 
' .0424 
Absolute alcohol. 
XI i 
3. 58 
24 
■ .0991 
Absolute ether... 
X4 j 
10.12 
.0149 
Petroleum ether.. 
xio 
46. 00 
' . 0386 
Absolute alcohol. 
XI 
3. 68 
38 
- .0557 
Absolute ether... 
X2 
6. 32 
. 1050 
Petroleum ether.. 
X20 
49.00 
. 0408 
Absolute alcohol. 
XI 
3. 63 
50 
■ .0513 
Absolute ether... 
XI 
3. 24 
. 1047 
Petroleum ether. . 
X20 
49. 00 
. 0420 
Absolute alcohol. 
XI 
3. 60 
71 
■ .1510 
Absolute ether... 
XI 
2. 05 
.0982 
Petroleum ether. . 
X20 
50. 40 
. 0439 
Absolute alcohol. 
XI 
3. 55 
111 
.3420 
Absolute ether... 
XI 
1.16 
.1020 
Petroleum ether.. 
X20 
50. 00 
. 0444 
Absolute alcohol. 
XI 
3.54 
143 
.4610 
Absolute ether... 
XI 
.83 
.0906 
Petroleum ether.. 
X20 
52. 40 
The results obtained in Table IV are 
graphically shown in Figure 1. Caro¬ 
tin apparently is just as stable in pe¬ 
troleum-ether solution as it is in alcohol 
solution. The rapid decline in the 
ether curve at once indicates that de¬ 
composition of the carotin in the ethe¬ 
real solution has been proceeding during 
the course of the experiment. The oxi¬ 
dation of the carotin may be due to 
the formation of peroxides (1) in the 
ether, as already pointed out. 
These facts are of importance to 
anyone who is interested in keeping 
carotin solutions for any purpose what¬ 
soever. The data for the alcohol so¬ 
lution show that it is possible to make 
up a standard solution of pure carotin 
in absolute alcohol and keep it for 
months, during which time it may be 
used for comparative work. The facts 
as observed are also of importance in 
connection with the method of deter¬ 
mining the amount of carotin in any 
substance—for example, in green leaves. 
In the method of separating the plant 
pigments, carotin is obtained in solu¬ 
tion in petroleum ether. This solution 
of carotin in petroleum ether may be 
stored in the ice chest for several days 
without fear of decomposition before 
making spectrophotometric, colorimet¬ 
ric, or comparison determinations of 
the amount of carotin which it con¬ 
tains. This is a decided convenience 
if a great number of determinations 
are to be made with a colorimeter, for 
such determinations can not be made 
at all on some days, nor at any time 
during the day, because of light condi¬ 
tions. 
SEPARATION AND PURIFICATION 
OF CAROTIN FROM CARROTS 
Carotin may be obtained from car¬ 
rots in the manner described below: 
After careful washing to remove any 
adhering dirt or foreign material, the 
carrots are sliced in a power slicer or 
by hand, using a vegetable slicer; the 
knives should be sharp, so as to injure 
the tissue as little as possible. The cut 
pieces should be about 4 mm. thick. 
The sliced carrots are placed on a 
large galvanized-iron wire tray and 
dried in an oven in which the tempera¬ 
ture is never allowed to exceed 50° C. 
Since destruction of a large percent¬ 
age of the carotin takes place during 
drying, the process should be carried 
on as rapidly as possible till the carrots 
are dry enough to grind in a power feed 
mill. The finely ground carrots will 
probably need to be dried further for 
several hours in a vacuum oven at less 
than 50° C. Grinding is rendered 
difficult if the material is not fully dry, 
as the presence of sugar in the carrots 
tends to clog the mill. After the final 
drying in the vacuum oven, the carrot 
meal is further ground in a ball mill 
(about 12 hours) till the greater part 
will pass a 40-mesh sieve. The finer 
it is ground, the more slowly the sol¬ 
vent will percolate and the higher will 
be the yield of the extracted pigment. 
The pulverized carrots (3 kgm.) are 
placed in a glass percolator (10 cm. in 
diameter at the top and 60 cm. long) 
provided with a layer of cotton in the 
bottom to prevent the fine red powder 
from going through, and the percolator 
is then attached to a large suction 
filter flask. Pure redistilled petroleum 
ether (B. P. 30° to 60° C.) is added and 
suction is applied till the solvent just 
begins to run through. More petro¬ 
leum ether is then added and allowed 
to percolate slowly overnight without 
using suction, when a large quantity of 
the colored extract will have passed 
