Book I. COMPOUND PRODUCTS OF PLANTS. 153 



684. Ofiohaltammn, or bnhnof&lead, which has been so much 687. Copal k the produce of therhus copalllmun, a tree which 

 fametl for its medical virtues. Is the produce of the amyris is found in North America. 



GileadensLs, a shrub which grows in Judaea and in Arabia ; but Anime, is obtained from the hymenaja coubaril, or locust-tree. 

 It is so much valued by the Turks that its importation is pro- a native of North America. 



hibited. This is the balm ofGilead so much celebratea in Lac is the produce of the croton laccifeium, a native of the 

 Scripture. Fliny says it was first brought to Rome by the East Indies. 



generals of Vespasian. It is obtained in a liquid state from 688. Bloom. Upon the epidermis of the leaves and fruit of cer- 

 incisions made in the bark, cuid is somewhat bitter to the taste. tain species of plants, there is to be found a fine, soft, and glaucous 



685. Copaiva, or balsam of copuiva, is obtained from the co- powder. It is particularly observable upon cabbage-leaves, and 

 paifera officinalis. upon plums, to which it communicates a peculiar shade. It 



Dragon's blond is obtained from the dracoena draco, pterocar- is known to gardeners by the name of bloom. It is easily rub- 

 pus draco, and calamus rotang. bed ofFby the fingers ; and when viewed under the microscope, 

 Gvaiac is the produce of the guaiacum officinale. seems to be composed of small opaque and unpolished granules, 

 Botany Bay resin, the produce of the acarois resinifera, a native somewhat similar to the powder of starch ; but with a high 

 of New Holland, and found in great abundance about Botany magnifying power it appears transparent. When rubbed off'. 

 Bay. it is again re-produced, though slowly. It resists the action 



686. G)-ecitr-f.5ZH constitutes the coloring matter of the leaves of of dews and rains, and is consequently insoluble in water, 

 trees, and of almost all vegetables. It is insoluble in water, b'lt But it is soluble in spirits of wine; from which circum- 

 Boluble in alcohol. When treated with oxymuriatic acid, it as- stance it has been suspected, with some probability, to be a 

 sumes the color of a withered leaf, and exhibits the resinous resin. 



properties more distuictly. 



689. The use of resins in the arts is very considerable ; but their medical virtues are not quite so 

 great as has been generally supposed. They are employed in the arts of painting, varnishing, embalm- 

 ing, and perfumery ; and they furnish us with two of the most imi^ortant of all materials to a naval 

 power, pitch and tar. 



690. Gum-resins. This term is employed to denote a class of vegetable substances, which have been 

 regarded by chemists as consisting of gum and resin. They are generally contained in the proper vessels 

 of the plant, whether in the root, stem, branches, leaves, ilowcrs, or fruit. But there is this remarkable 

 difference between resins and gum-resins, that the latter have never been known, like the former, to 

 exude spontaneously from the plant. They are obtained by means of bruising the parts containing tlicm, 

 and expressing the juice, which is ahvays in the state of an emulsion, generally white, but sometimes 

 of a different color ; or they are obtained by means of incisions from which the juice flows. This juice, 

 which is the proper juice of the plant, is -then exposed to the action of the sun, by which, in warm cli- 

 mates, it is condensed and inspissated, and converted into the gum-resin of commerce. Gum-resins, in 

 their solid state, are brittle, and less transparent than rosins. They have generally a strong smell, which 

 is sometimes alliaceous, and a bitter and nauseous taste. They are partially soluble both in water and in 

 alcohol. When heated, they do not melt like the resins, nor are they so combustible. But they swell 

 and soften by heat, and at last burn away with a flame. By distillation they yield volatile oil, ammonia 

 combined with an acid, and have a bulky charcoal. The principal species of gum-resins which have been 

 hitherto applied to any useful purpose are : — 



Galbanum, obtained from the stem of the bubon galhanum. Arabia. Bruce says it belongs to the genus mimosa; buthowever 



Ammoniac, brought from Africa in the form of small tears; this may be, myrrh is the juice of the plant concreted in the 



the plant which yields it is thought to be a species of ferula. form of tears. Its color is yellow, its odor strong but agree- 



Scammony, the produce of the convolvulus scaramonia. able, and its taste bitter ; it is employed in medicine, and is 



Opopmrnx, obtained from the pastinaca opoponax. esteemed an excellent stomachic. 



Euphorlnum, the produce of^ the euphorbia officinalis; its &yi. y44-5afa'<i(/a, a substance which is well known for its strong 



taste is caustic ; it is considered as a poison, but is occasionally and fetid smell, is obtained from the ferula assafoetida. At four 



employed in medicine. years old the plant is dug up by the root. 'I'he root is then 



Olibanum is obtained from the juniperus lycia, which grows cleaned, and the extremity cut oft'; a milky juice exudes which 



tn Arabia, particularly by the borders of the Red Sea. It is is collected; and when it ceases to flow another portion is cut 



the frankincence of the ancients. It exudes from incisions off', and more juice extricated. The process is continued till the 



made in the tree, and concretes into masses about the size of a root is exhauottd. The juice which has been collected soon 



chestnut. concretes, and constitutes assafoetida. It is brought to Kurope 



Sat^apenum is supposed to be obtained from the ferula in small agglutinated grains of different colors, white, red, 



persica. yellow. It is hard, but brittle. Its taste is bitter, and its 



Gamboge, or gumgutt, the produce of the mangostana cam- smell insufferably fetid ; the Indians use it as a seasoning for 



bogia. - their food, and call it the food of the gods. In Europe, it is 



691. Myrrh, the plant yieldingwhich grows in Abyssinia and used in medicine as an antispasmodic. 



693. Balsams. The substances known by the name of balsams are resins united to the benzoic ocid. 

 They are obtained by means of incisions made in the bark, from wliich a viscous juice exudes, whicli is 

 afterwards inspissated by the action of the lire or air, or they are obtained by means of boiling the i)L;rt 

 that contains them. They are thick and viscid juices, but become readily concrete. Their color is brown 

 or red ; their smell aromatic when rubbed; their taste acrid ; their specific gravity 1-090. They Rrc un- 

 alterable in the air after becoming concrete. They are insoluble in water, but boiling water abstracts 

 part of their acid; they are soluble in the alkalies and nitric acid. When heated they melt and swell, 

 evolving a white and odorous smoke. The principal of the balsams are the following : benzoin, storax, 

 styrax, balsam of tolu, balsam of Peru. 



Benzoin is the produce of the styrax benzoin. Balsam of tolu is obtained from the toluiferabalsamum. 



Storax is obtained from the styrax officinale. Balsam of I'eru is obtained from the myroxylon perui- 



Styrax is a semi-tluid juice, the produce ofa tree said to be ferum. 

 cultivated in Arabia. 



694. Camphor. The substance known by the name of camphor is obtained from the root and stem of 

 the laurus camphora, by distillation. When pure it is a white brittle substance, forming octagonal crystals 

 or square plates. Its taste is hot and acrid ; its odor strong but aromatic ; its specific gravity 0'9887. When 

 broke into small fragments and put into water, on the surface of which it swims, a singular pheno- 

 menon ensues. The water surrounding the fragments is immediately put into commotion, advancing and 

 retiring in little waves, and attacking the fragments with violence. The minuter fragments are driven 

 backwards and forwards upon the surfac^ as if impelled by contrary winds. If a drop of oil is let fall on 

 the surface of the water it produces an immediate calm. This phenomena has been attributed to elec- 

 tricity. Fourcroy thinks it is merely the effect of the affinities of the camphor, water, and air, entering 

 into combination. Though camphor is obtained chiefly from the laurus camphora, yet it is known to 

 exist in a great many other plants, particularly labiate plants, and has been extracted from the roots of 

 zedoary, sassafras, thyme, rosemary, and lavender. 



695 Caoutchouc. The substance denominated caoutchouc was first introduced into Europe about the 

 beginning of the eighteenth century. But from a use to which it is very generally applied of rubbing out 

 the marks made upon paper by a black-lead pencil, it is better known to most people in this country by the 

 name of Indian rubber. It is obtained chiefly from hsevea caoutchouc and jatropha elastica, trees indi- 

 genous to South America ; but it has been obtained also from several trees which grow in the East Indies, 

 such as ficus indicus, artocarpus integrifolia, and urceola elastica. If an incision is made into the bark of 

 any of these plants a milky juice exudes, which, when exposed to the air, concretes and forms caoutchouc. 

 As the object of the natives in collecting it had been originally to form it into vessels for their own use, it 

 it is generally made to concrete in the form of bags or bottles. This is done by applying the juice, wlien 

 fluid, in thin layers to a mould of dry clay, and then leaving it to concrete in the sun or by the fire. A 

 second layer is added to the firs-t, and others in succession, till the vessel acquires the thickness tliat is 

 wanted. The mould is then broken and the vessel fit^for use, and in this state it is generally brought into 

 p:uroi)c. It has been brought, however, even in its 'milky state, by Ix.-ing confined from the action of the 

 air. If the milky juice is exposed to the air, an clastic pellicle is formed on the surface. If it is confined 



