Why is the soap-tree so called?
Because its bark, if pulverized, and shaken in water, soon yields a solution, frothing, as if it contained soap. It is a native of Chili; the trunk is straight, and of considerable height; the wood is hard, red, and never splits; and the bark is rugged, fibrous, of ash-grey colour externally, and white within.
Why is a species of myrtle called the wax-tree?
Because the leaves and stem, when bruised, and boiled in water, yield wax, which concretes on cooling. Mr. Brande observes, "the glossy varnish upon the upper surface of many trees is of a similar nature; and though there are shades of difference, these varieties of wax possess the essential properties of that formed by the bee: indeed, it was formerly supposed that bees merely collected the wax already formed by the vegetable: but Huber's experiments show, that the insect has the power of transmuting sugar into wax, and that this is in fact a secretion."
The wax-palm of Humboldt has its trunk covered by a coating of wax, which exudes from the spaces between the insertion of the leaves. It is, according to Vaquelin, a concrete, inflammable substance, consisting of 1/3 wax, and 2/3 resin.
Why are some oils called vegetable butters?
Because they become solid at the ordinary temperatures. Such are cocoa-nut oil, palm oil, and nutmeg oil.
Why are some volatile oils obtained by expression?
Because they are contained in distinct vesicles in the rind of fruits, as in the lemon, orange, and bergamot.
Why is the oil of poppy-seed perfectly wholesome?