Olive.
The chief use of the olive, at least in this country, consists in the oil expressed from it. Unfortunately our so-called olive oil is generally cotton-seed oil. Captain Diamond of San Francisco, aged 111, and the oldest living athlete in the world, attributes much of his health to the use of olive oil. But he lays great stress upon the importance of obtaining it pure. Cotton-seed oil consists partly of an indigestible gum, and its continued ingestion tends to produce kidney trouble and heart failure.
A simple test for purity is to use, the suspected sample for oiling floors or furniture. If pure, it will leave a beautiful polish minus grease. But if it contains cotton-seed oil, part of it will evaporate, leaving the gummy portion behind.
When pure olive oil is shaken in a half-filled bottle, the bubbles formed thereby rapidly disappear, but if the sample is adulterated the bubbles continue some time before they burst.
Pure olive oil is pale and a greenish yellow.
If equal volumes of strong nitric acid (this may be obtained from any chemist) and olive oil are mixed together and shaken in a flask the resulting product has a greenish or orange tinge which remains unchanged after standing for ten minutes. But if cotton-seed oil is present, the mixture is reddish in colour, and becomes brown or black on standing.
Olive oil is slightly laxative, and therefore useful to sufferers from constipation. It is also an excellent vermifuge.
Olive oil has been used with great success in the treatment of gall stones. A Dr. Rosenberg reported that of twenty-one cases treated by "the ingestion of a considerable quantity of olive oil, only two failed of complete recovery."
Onion.
The uses of the onion are many and varied. Fresh onion juice promotes perspiration, relieves constipation and bronchitis, induces sleep, is good for cases of scurvy and sufferers from lead colic. It is also excellent for bee and wasp stings.