26 BULLETIN 1475, U. S. DEPARTMENT OF AGRICULTURE 
Perilla oil resembles linseed oil in odor and taste and has the prop- 
erty of absorbing more iodine than any other vegetable oil. The 
crude oil generally is dark yellow or greenish. For a long time it was 
considered to have drying properties inferior to those of linseed oil, 
because on drying it separated into drops when spread on a surface. 
With lead and manganese driers the oil dried unevenly in drops and 
streaks. Further study of the oil has shown several treatments which 
will make it dry evenly. When heated to about 482° F. for a short 
time or when blown with air at a temperature of about 257° F. for 
several hours, the oil no longer dries in droplets. Cobalt driers used 
with perilla oil in making paint or varnish make them dry quickly 
without any indication of streaks or unevenness. Furthermore, 
paints and varnishes made with perilla oil are said to have as much 
or more endurance than those made with linseed oil. Perilla oil, 
refined with sulphuric acid or caustic soda, is employed in the manu- 
facture of light- colored varnishes. 
The countries which produce perilla oil use it as a food and also 
for technical purposes, mainly in the manufacture of paints, var- 
nishes, printers' inks, and linoleum. It has been employed for many 
years in waterproofing paper and in making the cheaper grades of 
lacquers. In America and Europe it is used only for technical 
purposes. 
HEMPSEED OIL 
Hempseed oil is obtained from a plant {Cannabis sativa) which 
is cultivated for fiber and oil and as a drug. The plant is grown 
for fiber in India, Manchuria, and Europe and, on a comparatively 
small scale, in the United States. It is grown for the production of 
oil in China, Japan, Manchuria, and at times in Italy, France, and 
Russia. Large quantities of hempseed are imported into this coun- 
try from the Orient for use as birdseed and poultry feed. The 
domestic seed is used primarily for planting, because the imported 
seed is not satisfactory for this purpose. 
Hempseed contains about 30 per cent of oil, which when ex- 
pressed or extracted by solvents has a greenish color. 
Hempseed oil is employed chiefly as a paint oil, but in some coun- 
tries it is used as a lamp oil or converted into a dark-green soft soap. 
Its drying power is not so pronounced as that of linseed oil. 
POPPY-SEED OIL 
Poppy seed, which contains usually from 45 to 50 per cent of oil, 
'is grown in Europe, Asia Minor, Persia, India, and Egypt. It may 
be white, gray, blue, or red. The poppy seed imported into the 
United States is used chiefly for culinary purposes. The importa- 
tion of poppy-seed oil is very erratic, ranging from a few gallons up 
to more than 18,000 gallons per year. 
The pale cold-pressed oil, known on the market as white poppy- 
seed oil, has good keeping qualities. That expressed hot, commonly 
after the cold expression of the seed, is known as red poppy-seed 
oil. The white oil is used chiefly for edible purposes, although some 
is employed in the preparation of artists' paints. The lower grades 
are used for soap making. In most countries the press or oil cake 
is used as a cattle food; in India it is used as food for the poorer 
classes. 
