_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.