26 
BULLETIN 1471, V. S. DEPARTMENT OF AGRICULTURE 
Table 18. — How the refractive index of halo wax oil is chan-ged per 1 per cent 
of linseed oil present 
[Readings taken at 25° C] 
Change in 
Difference 
Percentage 
Refractive 
refractive 
in refrac- 
of linseed 
index of 
index of 
tive index 
oil in 
halowax- 
halowax oil 
of halowax 
halowax 
linseed oil 
due to 
per 1 per 
oil 
mixture 
linseed oil 
cent of lin- 
present 
seed oil 
10. 697 
1. 61313 
0. 02041 
0. 001908 
10. 983 
1. 61255 
. 02099 
.001911 
12. 099 
1. 61048 
.02306 
. 001906 
13.100 
1. 60863 
. 02491 
.001902 
13.546 
1. 60779 
. 02575 
. 001901 
14. 237 
Average-. 
1. 60636 
. 02718 
. 001909 
.001906 
Refractive index of halowax oil, 1.63354. 
Each factor in the Wesson method (9), as it related to flaxseed, 
was studied step by step, to obtain greater refinement and to obtain 
closer agreement with the ether-extraction method of the Association 
of the Official Agricultural Chemists (1 p. 72, Nos. 9, 10, 11) and 
after considerable effort the following method was evolved, here- 
after called the optical method : 
DESCRIPTION OF TEST 
Apparatus required: 
One motor-driven experimental flouring mill with 6 by 6 inch rolls, corru- 
gated 40 to the inch. 
Six 3-inch porcelain mortars, with pestles. 
One analytical balance, sensitive to one-tenth of a milligram. 
One electric hot plate, 8 by 8 inches. 
One 25 cubic centimeter Shellbach burette. 
Two dozen test tubes 5 by one-half inches, with wire rack for holding same. 
Two dozen 40-millimeter glass funnels. 
Supply of halowax oil, No. 1000 or No. 1007. 
Supply of folded filter paper, absorbent cotton, and glass rods. 
One fifth decimal place water-jacketed refractometer. 
One temperature-regulating device. 
Two 25 cubic centimeter pycnometers. 
An assembled unit is shown in Figure 1. 
DIRECTIONS FOB PREPARATION OF CONVERSION TABLES 
(1) Into three 4-ounce bottles, previously weighed, place approxi- 
mately 25 cubic centimeters of halowax oil and note the exact weight 
of the halowax oil added to each bottle. Next add linseed oil to 
each of the three bottles so that, by weight, a 10, a 12, and a 14 per 
cent solution of linseed oil in halowax oil will be obtained. Addi- 
tional mixtures may be made if desired, but three will usually be 
enough. It is not necessary to obtain even percentages of linseed oil 
in the mixture. As the optical method is standardized against the 
ether-extraction method, linseed oil obtained by ether extraction is 
used for making up the mixtures with halowax oil. 
When the bottles containing the known percentages of linseed oil 
have been thoroughly mixed, read the refractive index of each mix- 
