The leading industry of this ranch is to be the making of olive oil. Already its oil is known and sought; and to taste it is a revelation to palates accustomed to the compounds of rancid cocoanut and cotton-seed with which the markets are full. The olive industry will no doubt ultimately be one of the great industries of the whole country: vast tracts of land which are not suitable or do not command water enough for orange, grape, or grain culture, affording ample support to the thrifty and unexacting olive. The hill-slopes around San Diego, and along the coast line for forty or fifty miles up, will no doubt one day be as thickly planted with olives as is the Mediterranean shore. Italy's olive crop is worth thirty million dollars annually, and California has as much land suited to the olive as Italy has.
The tree is propagated from cuttings, begins to bear the fourth year, and is in full bearing by the tenth or twelfth. One hundred and ten can be planted to an acre. Their endurance is enormous. Some of the orchards planted by the friars at the missions over a hundred years ago are still bearing, spite of scores of years of neglect; and there are records of trees in Nice having borne for several centuries.
The process of oil-making is an interesting spectacle, under Mr. Cooper's oak trees. The olives are first dried in trays with slat bottoms, tiers upon tiers of these being piled in a kiln over a furnace fire. Then they are ground between stone rollers, worked by huge wheels, turned by horse-power. The oil, thus pressed out, is poured into huge butts or tanks. Here it has to stand and settle three or four months. There are faucets at different levels in these butts, so as to draw off different layers of oil. After it has settled sufficiently, it is filtered through six layers of cotton batting, then through one of French paper, before it is bottled. It is then of a delicate straw color, with a slight greenish tint,--not at all of the golden yellow of the ordinary market article. That golden yellow and the thickening in cold are sure proofs of the presence of cotton-seed in oil,--the pure oil remaining limpid in a cold which will turn the adulterated oils white and thick. It is estimated that an acre of olives in full bearing will pay fifteen hundred dollars a year if pickled, and two thousand dollars a year made into oil.