148 



HISTORY OF THE VEUETABLE KINGDOM. 



Botany Bay resin. This resin is said to be 

 the produce of the acarois resimfera,a,tTee wliich 

 grows abundantly in New Holland, especially 

 near Botany Bay. The resin exudes spontan- 

 eously from the trunk of the singular tree which 

 yields it, especially if the bark be wounded. It 

 is at first fluid, but becomes gradually solid when 

 dried in the sun. It is insoluble in water, but 

 comnmnicates to that liquid the flavour of 

 storax. Alcohol dissolves it. 



Green resin. This resin constitutes the colour- 

 ing matter of the leaves of trees, and of almost 

 all veg^ables. It is insoluble in water, but sol- 

 uble in alcohol. When treated with oxymuriatic 

 acid it assumes the colour of a withered leaf, 

 and exhibits the resinous properties more dis- 

 tinctly. 



Copal. This resin is obtained from the rhus 

 copallinium, a tree which is found in North 

 America. It is a transparent substance, with a 

 slight tinge of brown. It possesses the general 

 properties of other resins, but differs from them 

 in not being soluble in alcohol or oil of turpen- 

 tine, without peculiar management. When 

 dissolved in any volatile liquid, and spread thin 

 upon wood, metal, or paper, so that the volatile 

 menstruum may evaporate, it foiTns one of the 

 most perfect and most beautiful of all the var- 

 nishes, known by the name of Copal varnish. 

 For this purpose it is generally dissolved in oil 

 of turpentine. 



Anime. This resin is obtained from the Jiy- 

 mcnwa courharil, or locust tree, a native of North 

 America. It resembles copal exactly in its ap- 

 pearance, but differs from it in being readily 

 soluble in alcohol. It is employed also in mak- 

 ing varnishes. 



Lac. This resin is the produce of the croton 

 lacciferum, a native of the East Indies. It ex- 

 udes in consequence of the puncture of an in- 

 sect, whence it is supposed to derive its colour, 

 which is deep red verging to brown, with a de- 

 gree of semi-transparency. It forms the basis of 

 many varnishes, and of the finest kinds of seal- 

 ing wax. 



Bloom. Upon the epidermis of the leaves 

 and fruits of certain species of plants, there is 

 to be found a fine soft and glaucous powder. It 

 is particularly observable upon cabbage leaves, 

 and upon plums, to which it communicates a 

 particular shade. It is known to gardeners by 

 the name of bloom. It is easily rubbed off by 

 the fingers, and when viewed under the micros- 

 cope seems to be composed of small opaque and 

 unpolished granules, somewhat similar to the 

 powder of starch; but with a high magnifying 

 power it appears transparent. When rubbed 

 off it is again reproduced, though slowly. It 

 resists the action of dews and rains, and is con- 

 sequently insoluble in water. But it is soluble 

 in alcohol, from which circumstance it has 



been suspected with some probability to be a 

 resin. 



Such are some of the most remarkable of the 

 resins that have been subjected to chemical analy- 

 sis, or employed in medicine or the arts. Their 

 medical virtues, however, are not quite so great 

 as has been generally supposed, but their utility 

 in the arts is very considerable. They are em- 

 ployed in the arts of painting, varnishing, em- 

 balming, and perfumery; and they furnish us 

 with two of the most important of all materials 

 to a naval power, pitch and tar. 



Gum resins. There are many plants which, 

 when cut or pierced, give out a milky juice more 

 or less thick. This juice has generally a strong 

 taste, and frequently also a peculiar smell. These 

 milky juices are contained in the living plant in 

 a peculiar set of vessels, which usually mn along 

 the interior part of the bark. The common 

 leontodon taraxictim, lactuca irirosa, the different 

 species of euphorbia, and the poppy, may be 

 mentioned as examples of plants yielding these 

 milky juices. When the milky juice is made 

 to exude from a plant, and then exposed to 

 the atmosphere, it becomes solid, and assumes 

 different appearances according to the plant from 

 which it is obtained. Now these concrete juices 

 are the substances which have .long been distin- 

 guished by the name of gum resins. Gum resins 

 are usually opaque, or at least their transparency 

 is inferior to that of resins. They are always 

 solid, and most commonly brittle, and have 

 sometimes a fatty appearance. When heated 

 they do not melt as the resins do, neither are 

 they so combustible. Heat, however, commonly 

 softens them, and causes them to swell. They 

 bum with a flame. They have almost always 

 a strong smell, which, in several instances, is 

 similar to that of garlic. Their taste also is 

 often acrid, and much stronger than that of the 

 resins. They are partially soluble in water, but 

 the solution is always opaque, and usually 

 milky. Alcohol dissolves only a portion of 

 them, the solution is transparent; but when di- 

 luted with water it becomes milky. They dis- 

 solve much better in dilute alcohol. 



Galbanum. This substance is obtained &om 

 the htbon galbanum, a perennial plant found at 

 the Cape of Good Hope. An incision is made 

 in the stem a little above the root, and the milky 

 juice flows out. When it concretes it consti- 

 tutes galbanum. It is brought into this country 

 in small pieces, composed of agglutinated tears 

 of a yellow colour, acrid and bitter taste, and 

 smell of garlic. Water, vinegar, and wine, dis- 

 solves the greater part of it, but the solution is 

 milky. It is chiefly used in medicine. 



Ammoniac. This substance is brought from 

 Africa in the form of small tears, but nothing 

 certain is known concerning the plant which 

 yields it. It is thought to be a species of ferula. 



