Bombacem.—Adansonia digitata.
Stcrculiacece.—Bombax spp. ; Stcrculia spp. (contributing to Kuteera).
Cactaoecs.—Cactu,s spp. ; Opuntia spp.
Moringacem.—Moringa pterygosperma (Moringa).
Bromeliacece.—Puya spp. (Chagual).
Pahruiceo3.—Cocos nucifera (Coco-nut).
Gums may be divided into the following four classes :— (1) Arabinic.—Theae consist essentially of arabine ; eerasine and bassorine are eithor quite absent, or in very minute proportion. Tho chief arc—Arabic (all kinds), Wood-apple, and Cialjii gums.
(2) Cerasinic.—Contain varying proportions of canaille and arabine. The Cherry group.
(3) Bassorinic.—Essentially cornpuaed of bassorine. Embraces Tragacanth, Kuteera, Coco-nut, Chagunl, and Moringa gums.
(4) Cerasiuo-bassorinic.—Compounded of ecrasine and bassorine. Kuteera (sonie kinds).
2. Itsams.— Under the term " resins," are included all the hard, friable, natural plaut-substances, externally resembling gurus ; insoluble in water ; soluble in etber and alcohol ; rich in carbon ; poor in oxygen ; free from nitrogen ; and burning with a smoky flume. No resin is a definite chemical compound, but rather a complicated mixture. The essential ingredients of resins are the reain-acids—substancea rich in carbon ; some of thcm displace the carbonic acid in alkaline carbonates, and form with the alkalica the ao-called resin-soaps, which froth in water. Besides the resin-acida, natural resins contain volatile oils, gurna, and often cinnamic nnd beuzoio acids, as well as the ordinary compouenta of plant-tissues--cellulose, tannin, hurnic bodies.
The older ohemists classified resins into " hard," " soft," and " feather." The two first are now combined as " resina" simply, their difference iu hardness being only a matter of degree, while most of the soft resins become bard in time. "Feather" resins denoted indiaruhbers, which are now excluded from the resiva altogether, on the ground of both physical and chemical dissimi larities, and will receive a separate description. The usual classification now adopted by Continental chemists is threefold :—(1) True resins, (2) gum-resins, (3) balsams. Tho gum-resins differ from true resins only in containing some gum. Balaama include both reaina which are rich in volatile
oil, the latter assuming a reainous charaoter, or holding a great portion of the resin in solution, thus forming a ayrupy mass (suoh as turpentine and Canada halaam) ; and bodies which in outward character resemble the resinous balsams (like Peru), and are chemically poor in reainoua matters, though rich in a fluid neutral aubstanoe bearing some likeness to certain resina. The claasifieation adopted by M. C. Cooke differs considerably from the foregoing. Omitting the gums, which have been already dealt with, be forms three groups—gum-resins, resina, and oleo-reaina. The gum reaina embrace three classes—emulaive, fetid, and fragrant, the last being again sub-divided into sections, represented respectively by bdellium and benzoin. The true resins he distinguishes as hard or copslline (sub-classified as pale and dark), and soft or elemi. While his oleo-resins embrace balsams, natural varnishes, and turpentines and tars (the two last grouped together). 'Usually in England, however, the term gum-resin is applied to an inspissated milky plant juice, consisting of a gum soluble in water, associated with a resin and a volatile oil soluble in alcohol, and containing other vegetable and a little mineral matter. The general acceptation of the term " balsam " is an olco-reain, or natural compound of a resin and an essential oil, in auch proportions as te form a viscaua or aemifluid mass. From the solid resin to the limpid essential oil are insensible giadations, and few resins are hard at the moment of their exudation. The proposal to confine the terrn balsam to such bodies as contain cinnamic (or an analogous) acid, in addition to the resin and essential oil composing tho oleo-resin, has not been carried out; but the fragrant balsams containing cinnamic or benzoic acids are regarded as a distinct class by authorities on materia medics, though Cooke includes under the term all the oleo-resins, except the natural varnishes (acrid lacquers) and the turpentines and tars.