Oil of bitter almond is formed by the action of the amygdalin upon the emulsin present in the fruit, bitter-almond meal being deprived of fat and left in contact with water for some hours at from 40-45° C. (104-113° F.). Besides oil of bitter almond, sugar and prussic acid are likewise formed. The crude oil distilled from the meal is freed from the prussic acid by agitation with ferrous chloride and lime-water, and redistillation. OIL OF CAJEPUT (OLEUM CAJUPUTI) has usually a greenish color, and has a burning, camphoraceous and at the same time cooling taste. It has a peculiar odor resembling that of camphor and rosemary. OIL OF CALAMUS (OLEUM CALAMI). This oil, which is very viscid and of a yellow or reddish color, must usually be mixed with other essential oils in order to furnish pleasant perfumes. OIL OF CHAMOMILE (OLEUM CHAMOMILLÆ). Oil of chamomile, from Matricaria Chamomilla (common chamomile), which is specially characterized by its magnificent dark-blue color, has a marked narcotic odor and is very high-priced, owing to the small yield of oil by the flowers. The oil from Anthemis nobilis (Roman chamomile) has also a blue color which gradually becomes greenish-yellow. CAMPHOR (CAMPHORA). This essential oil differs from the others mainly by being firm and crystalline at ordinary temperatures. Chinese or Japanese camphor melts at 175° C. (347° F.) and boils at 205° C. (401° F.). Camphor is seldom used alone, as its odor is hardly fragrant; but it finds frequent application in the preparation of mouth washes, toilet vinegars, etc. In commerce so-called Borneo camphor is also met with (though rarely), which closely resembles the Chinese in appearance and other qualities, but is more friable and melts at 189° C. (388·4° F.). OIL OF CASCARILLA is not used pure in perfumery, the bark being generally employed instead. OIL OF CASSIA (OLEUM CASSIÆ) has a yellow color, gradually becoming dark reddish-brown, and an odor resembling that of oil of cinnamon, but the odor is not so fine, nor so strong, as that of the latter. The taste of the oil is of special importance: while that of true oil of cinnamon is burning though sweet, oil of cassia has a sharper taste, and this taste is considered by some a good mark of recognition of the rather common adulteration of true oil of cinnamon which is much more costly. OIL OF CEDAR. This oil, obtained from the wood of the Juniperus virginiana (not from the true cedar, Cedrus Libani), is clear like water, has a pleasant odor, and differs from most essential oils by congealing at a very low temperature (-22° C. or-8° F.) and by its uncommon resinification in contact with air. OIL OF CITRON.