Among the various seeds used in the manufacture of oil-cake, flour of linseed is the most important.  Rape seed is also employed, but is considered heating.  In Lubeck, a marc, called dodder cake, is made from the Camelina sativa.  Inferior oil-cake is made from the poppy in India.  Cotton-seed cake has lately been recommended on account of its cheapness, being usually thrown away as refuse by the cotton manufacturers.  It is extensively used as a cattle food, in an unprepared state, in various parts of the tropical world, and to a limited extent in this country.

The cost of seed, freight included, was 2d. per lb. from Charlestown to Port Glasgow.  Cotton oil-cake is now ordered at the same price as linseed cake.  The produce of oil-cake and oil from cotton seed, is two gallons of oil to one cwt. of seed, leaving about 96 lbs of cake; 8 lbs. is the daily allowance for cattle in England.

Cotton seed oil, very pure, is manufactured to a considerable extent at Marseilles, by De Gimezney, from Egyptian seed; and he received a prize medal at the Great Exhibition.

Account of the export of linseed and rapeseed cakes from Stettin, principally to England, in—­

cwts.
1834        33,518
1835        27,038
1836        56,581
1837        70,643
1838       119,540
1839       115,416
1840       162,457
1841       143,816
1842       119,814

The quantity of oil-seed cakes imported into the United Kingdom was in—­

tons.
1849       59,462
1850       65,055
1851       55,076
1852       53,616

Cargoes of oil-cake, to the value of L22,207, were exported from the port of Shanghae, in China, in 1849.

2,467 tons of oil-cake were brought down to New Orleans from the interior in 1848, and 1,032 tons in 1849.

Seven samples of American oil-cake gave the following results:—­

Oil        11.41
Water       7.60
Nitrogen    4.74
Ash         6.35

From the above figures, the scientific farmer will see that the manure formed by 100 lbs. of oil-cake is more than that derived from 300 lbs. of Indian corn. 300 lbs. of corn contain about l1/4 lbs. phosphoric acid; 100 lbs. oil-cake contain about 21/2 lbs.

VOLATILE OR ESSENTIAL OILS occur in the stems, leaves, flowers and fruit of many odoriferous plants, and are procured by distillation along with water.  They are called “essences,” and contain the concentrated odor of the plant.  They usually exist ready-formed, but occasionally they are obtained by a kind of fermentation, as oil of bitter almonds and oil of mustard.  Some of them consist of carbon and hydrogen only, as oil of turpentine, from Juniperus communis; oil of savin, from Juniperus Sabina; oil of lemons and oranges, from the rind of the fruit; and oil of nerole, from orange flowers.  A second set contain oxygen in addition, as oil of cinnamon, from Cinnamonum verum; otto or attar of roses, from various species of rose, especially Rosa centifolia; oil of cloves, from Caryophyllus aromaticus.