VEGETABLE SUBSTANCES. To treat of botanical classification, or of the pheno mena of vegetable growth, be beyond the limits of the present work. In respect to the vegetable substances employed in food, medicine, and the arts, many are described under their proper headings.
When the Commissioners were forming the skeleton for the arrangements of the Great Exhibition, they devoted one of the four sections of the entire collection to Raw Materials arid Produce; and this section they divided into animal, vegetable, and mineral. It may be useful to give here, in an abridged form, the system on which vegetable sub stances were divided.
The whole series of vegetable substances, so far as usefully employed, were placed in four groups: 1st. Substances used chiefly in food; 2nd. Materials used chiefly in the chemi cal or medical arts ; 8rd. Materials for build ing, clothing, dtc. ; 4th. Miscellaneous substances.
The first group comprised agricultural pro duce, such as corn, pulse, oil seeds, &c.; dried fruits and seeds ; substances used in the preparation of drinks ; spices and condi ments; different varieties of starch ; different varieties of sugar; fermented liquors and dis tilled spirits from unusual sources. The
second group comprised different varieties of gum ; resins, such as balsams, gum resins, and elastic gums ; oils, such as volatile oils, fat oils, drying oils, solid oils, and wax; acids and alkalies ; dyes and colours ; tanning sub stances ; intoxicating drugs; medicinal sub stances. The third group comprised fibrous substances, such as cordage and clothing materials ; cellular substances ; timber and fancy woods. The last group, as its name pretty nearly implies, comprised all the sub stances which could not very well be included under any of the other three, and which were necessarily of a diverse character.
So far as was practicable, this system of classification has been attended to in the arrangement of the Exhibition ; but it has un avoidably happened that some of the varieties are less fully represented than others.