The reason why : $b a careful collection of many hundreds of reasons for things which, though generally believed, are imperfectly understood. A book of condensed scientific knowledge for the million — John Stuart Mill — John Shaqi
The reason why : $b a careful collection of many hundreds of reasons for things which, though generally believed, are imperfectly understood. A book of condensed scientific knowledge for the million
John Stuart Mill · en
The ocean as well as the land has different botanical regions; and
changes of the vegetation are observed with the depth analogous
to the variations of terrestrial plants with the height. Marine
vegetation seems to have its vertical extent determined by the
range of light in water, which varies with the power of the sun
and the transparency of the water.
CHAPTER LXIII.
1254. _What are vegetable gums?_
Vegetable gums are secretions of plants which are generally _soluble in
water_, and which subserve various useful purposes. _Gum Arabic_ is one
of the most important of this class of vegetable productions.
_Gutta-percha_ is an invaluable substance lately added to the list of
known vegetable productions. It is obtained by cutting the bark of
trees of the class called _Sapotacea_. Its proper name is gutta Pulo
Percha, gutta meaning gum, and Pulo Percha is the island whence it is
obtained. But gutta-percha is not, strictly speaking, a gum.
_India-rubber_ is also a vegetable secretion, improperly called elastic
gum. It is obtained from the milky juice of various trees and plants,
especially from the syringe tree, of Cayenne.
1255. _What are vegetable resins?_
_Vegetable_ resins are derived from the secretions of plants, and are
generally distinguished from gums by being _insoluble in water_, but
being soluble in spirits.
When one of these substances is soluble in either water or spirits it
is called a _gum-resin_.
1256. _What are vegetable acids?_
Vegetable acids are chiefly obtained from _fruit_; but also abundantly
from _wood_, by distillation.
[Verse: "Thou art the God that doest wonders."--PSALM LXXVII.]
1257. _What is tannin?_
Tannin is a vegetable production, obtained chiefly from the oak-bark,
and from a variety of other vegetable sources. It possesses the
peculiar chemical property which renders it valuable in tanning leather.
1258. _What is opium?_
Opium is the produce of the _poppy_, and is obtained from the seed.
1259. _What are vegetable dyes?_
Vegetable dyes are the various colours derived from the secretions of
plants, such as _indigo_, _madder_, _logwood_, _alkanet-root_, _&c._
1260. _What is silica?_
Silica is a mineral substance, commonly known as _flint_; and it is
one of the wonders of the vegetable tribes, that, although flint is
so indestructible that the strongest chemical aid is required for its
solution, plants possess the power of _dissolving and secreting_ it.
Even so delicate a structure as the wheat straw dissolves silica, and
every stalk of wheat is covered with a perfect, but inconceivably thin
coating of this substance.