146 



HISTORY OF THE VEttETABLE KINGDOM. 



ing candles; and hence an explication of this 

 singular phenomenon observable in the pictam- 

 ntts fraxinella. This plant is fragrant, and the 

 odour which it diffuses around forms a partial 

 and temporary atmosphere, which is inflammal)le; 

 for if a lighted candle or other ignited body is 

 brought near to the plant, especially in the time 

 of drouglits, its atmosphere immediately takes 

 fire. This phenomenon was first observed by 

 the daughter of the celebrated Linnceus, and is 

 explained by supposing the partial and tempor- 

 ary atmosphere to contain a portion of wax ex- 

 uded from the plants, and afterwards reduced to 

 vapour by the action of the sun. The result of 

 its combustion in oxygen gas was, according to 

 Lavoisier, carbonic acid and water, in such pro- 

 portions as to lead him to conclude that 100 

 parts of wax are composed of 82.28 of carbon, 

 and 17.72 of hydrogen. But owing to the little 

 action of acids on it, there seems reason to be- 

 lieve that it contains also oxygen as an ingre- 

 dient. Wax possesses all the essential properties 

 of a fixed oil. But fixed oils have the property 

 of becoming concrete, and of assuming a waxy 

 appearance when long exposed to the air, in 

 consequence, as it seems, of the absorption of 

 oxygen. Wax, therefore, may be considered as 

 a fixed oil rendered concrete, perhaps by the 

 absorption of oxygen during the progress of vege- 

 tation. But if this theory is just, the wax may 

 be expected to occur in a considerable variety of 

 states, according to its degree of oxygenation, 

 and this is accordingly the case. Sometimes it 

 has the consistency of butter, and is denominated 

 butter of wax, as butter of coco, butter of galam; 

 sometimes its consistency is greater, and then it 

 is denominated tallow, as tallow of croton; and 

 when it has assumed its last degree of consis- 

 tency, it then takes the appellation of wax. The 

 butter of cacao is extracted from the seeds of 

 the theobroma cacao, or chocolate plants, either 

 by boiling them in water, or by subjecting them 

 to the action of the press, after having exposed 

 them to the vapour of boiling water. They 

 yield almost half their quantity of butter. It 

 is at first brovm or yellow, but when well puri- 

 fied it is white; its taste is sweet, its fracture 

 slightly granular, and its touch unctuous. It 

 is to this butter that chocolate owes its flavour 

 and unctuosity. Butter of coco is found in the 

 fruit of the coco-nut tree. It is expressed from 

 the pulp of the nut, and is even said to separate 

 from it when in a fluid state, as cream separates 

 from milk. Butter of nutmeg is obtained from 

 the seeds of the myristica officinalis, or nutmeg 

 tree. They are pounded and formed into a paste 

 with water, and then subjected to the action of 

 the press. The butter is firm and orange coloured, 

 and of a sweet and aromatic smell. From the 

 croton scbiferum, a tree that grows in Asia and 

 America, a waxy substance is extracted, of the 



consistence of tallow. It adheres to the surface 

 of the fruit, and is detached from it by means 

 of boiling the fruit in water. Its odour is rather 

 pleasant, but it acts as a violent purgative. The 

 Chinese use it in the manufacture of candles. 



The myrica cerifera, a plant which grows 

 abundantly in Louisiana and other parts of North 

 America, furnishes the wax of myrtle. The 

 berries, which are about the size of a pepper 

 corn, are gathered and thrown into a kettle 

 which is nearly filled with water. The water 

 is then made to boil, and the wax which is ex- 

 tracted floats on the surface. It is of a pale 

 green colour; its specific gravity is 1.0150, it 

 melts at the temperature of 109°; and when 

 strongly heated burns with a white flame pro- 

 ducing smoke, and emitting an agreeable odour. 

 Wax is also extracted from a variety of other 

 vegetables, and has been detected by Proust in 

 the green fecula of many plants, as in that of 

 the cabbage. He considers it as a constituent 

 part of the pollen of all flowers, and thinks that 

 the bees collect it along with the gluten of the 

 pollen, which, according to him, serves them for 

 food. Certainly it is one of the most abundant 

 of vegetable principles, and is of great utility 

 both in medicine and in the arts. Its soft and 

 unctuous qualities render it fit for being em- 

 ployed as an ingredient in ointments and plasters, 

 and in a great variety of other medicaments. It 

 is employed also by the sculptor, statuary, and 

 modeller, in the exercise of their arts. But its 

 chief utility consists in its being better adapted 

 than all other substances for tlie manufacture 

 of candles. The candle burns with a clear and 

 brilliant flame, and the wick needs no snufling. 



Resins. The term resina was given by the 

 ancients to the expressed juice of certain pine 

 trees, and coiTesponds to our common resin. 

 Many vegetables yield a resinous juice. It is 

 obtained either by exudation from trees, or by 

 digesting the substance containing the resin in 

 alcohol. In the first case, it exudes from natural 

 or artificial openings in the bark and part of 

 the wood of trees. The resin flows out in sum- 

 mer in a liquid state, it being held in solution 

 by a volatile oil, which, when the exudation is 

 exposed, to the air, either makes its escape or is 

 converted into resin by the absorption of oxygen. 

 When this change takes place the liquid is con- 

 verted into a solid resin. In the second place, 

 the alcoholic solution being diluted with water, 

 the resin falls down, and the alcohol is recovered 

 by distilling the diluted liquor. 



Resins are solid substances, naturally brittle, 

 have a certain degree of transparency, and a 

 colour most commonly inclining to yellow. 

 Their taste is insipid, and they have no smell 

 except when they retain a portion of volatile 

 oil, in which case they partake of the odour and 

 acrid taste of that oil. They are insoluble in 



