CHEMISTRY. 



123 



Chemical 



Examina- 

 tion of 

 Nature. 



{hndarach, 



Elcrni, 



Tacama- 

 hac, 



Anime, 



Lidanum, 



Botany 

 Bay resin, 



examined by Kind, who found it possessed of all the 

 properties of caoutchouc. These experiments have lately 

 been repeated by Mr Matthews with a similar result. 

 Mr Brande, however, has observed, that when this in- 

 soluble substance is dried, it becomes brittle, in which 

 respect it differs from caoutchouc. He has observed also, 

 that by passing a current of ox-ymuriatic gas through the 

 alcoholic solution of mastich, a tough elastic substance 

 is thrown down, precisely similar to the original insolu- 

 ble portion. 



3. Sandarach. This resin is obtained from the jttni- 

 penis cammunis, or common juniper. It exudes spon- 

 taneously, and is usually in the state of small round tears 

 of a brown colour, and semitransparent, iiot unlike mas- 

 tich, but rather more transparent and brittle. When 

 chewed it does not soften as mastich does, but crumbles 

 to powder. Mr Matthews found it almost completely 

 soluble in eight times its weight of alcohol. The resi- 

 due was extraneous matter. It does not dissolve in tal- 

 low or oil, as common resin does. 



4-. Elenii. This resin is obtained from the amyris ele- 

 mlfera ; a tree which grows in Canada and Spanish Ame- 

 rica. Incisions are made in the bark during dry weather, 

 and the resinous juice which exudes is left to harden in 

 the sun. It comes to this country in long roundish 

 cakes wrapped in flag leaves. It is of a pale yellow 

 colour, semitransparent ; at first softish, but it hardens 

 by keeping. Its smell is at first strong and fragrant, 

 but it gradually diminishes. 



5. Taramuhac. This resin is obtained from the faga- 

 ra octandra, and likewise, it is supposed, from the popu- 

 lus biilsamifera. It comes from America in large ob- 

 long masses wrapt in flag leaves. It is of a light brown 

 colour, very brink, and easily melted when heated. 

 When pure it has an aromatic smell between that of la- 

 vender and musk. 



6. Animf. This resin is obtained from the Jiymciuea 

 courbaril, or locust tree, which is a native of North A- 

 merica. Anime resembles copal very much in its ap- 

 pearance ; hut is readily soluble in alcohol, which co- 

 pal is not : this distinguishes them. It is said to be very 

 frequently employed in making vaniishc.-. Alcohol dis- 

 solves it completely. 



7. Ladanum or labrlanttm. This resin is obtained 

 from the cysttii crrticvt, a shrub which grows in Syria 

 and the Grecian Islands. The surface of this shrub is 

 covered with a vise-id juice, which, when concreted, forms 

 ladanum. It is collected, while moist, by drawing over 

 it a kind of rake with thongs fixed to it. From these 

 thongs it is afterwards scraped with a knife. It is always 

 nixed with dust and sand, sometime* in great abun- 

 dance. The best it in dark coloured masses, almost 

 black, and very soft, having a fragrant odour and a bit- 

 terish taste. The impurities, even in the best kinds, 

 amount to about one-fourth. 



8. Botany Bay resin. This resin is said to be the 

 produce of the acaroit resinifera ; a tree which grows 

 abundantly in New Holland, especially near Botany 

 Bay. Specimens of it were brought to I,ondon about 

 the year 1799, where it was tried as a medicine. 



The resin exudes spontaneously from the trunk of the 

 singular tree which yields it, especially if the bark be 

 wounded. It it at first fluid, but becomes gradually 

 solid when dried in the sun. It consists of pieces of va- 

 rious sizes, of a yellow colour, unless when covered 

 with a greenish grey crust. It is firm, yet brittle ; and 

 when pounded, does not stick to the mortar nor cake. 

 In the mouth it is easily reduced to powder without 

 ticking to the teeth. It communicates merely a slight 



Chemical 

 Examina- 

 tion of 

 Nature. 



sweetish astringent taste. When moderately heated, it 

 melts ; on hot coals it burns to a coal, emitting a white 

 smoke, which has a fragrant odour somewhat like sto- 

 rax. When thrown into the fire, it increases the flame 

 like pitch. It communicates to water the flavour of 

 storax, but is insoluble in that liquid. When digested 

 in alcohol, two thirds dissolve: the remaining third con- 

 sists of one part of extractive matter, soluble in water, 

 and having an astringent taste ; and two parts of 

 woody fibre and other impurities, perfectly tasteless 

 and insoluble. The solution has a brown colour, and 

 exhibits the appearance and the smell of a solution of 

 b. nzoin. Water throws it down unaltered. When dis- 

 tilled, the products were water and empyreumatic oil, 

 and charcoal ; but it gives no traces of any acid, alkali, 

 or salt, not even when distilled with water. 



9. Copal. This substance, which deserves particular Copal, 

 attention from its importance as a varnish, and which at 

 first sight seems to belong to a distinct class from the 

 resins, is obtained, it is said, from the rhuf copallinum, 

 a tree which is a native of North America ; but the best 

 sort of copal is said to come from Spanish America, and 

 to be the produce of different trees. No less than eight 

 species are enumerated by Hernandez. 



Copal is a beautiful white resinous substance, with a 

 slight tint of brown. It is sometimes opaque, and some- 

 times almost perfectly transparent. When heated, it 

 melts like other resins ; but it differs from them in not 

 being soluble in alcohol, nor in oil of turpentine without 

 peculiar management. Neither does it dissolve in the 

 fixed oils with the same ease as the other resins. It re- 

 sembles gum anime a little in appearance ; but is easily 

 distinguished by the solubility of this last in alcohol, and 

 by its being brittle between the teeth, whereas anime sof- 

 tens in the mouth. The specific gravity of copal varies, 

 according to Brisson, from 1.045 to 1.139. Mr Hatch- 

 ctt found it soluble in alkalies and nitric acid with the 

 usual phenomena ; so that in this respect it agrees with 

 the other resins. The solution of copal in alkalies he 

 found indeed opalescent, but it is nevertheless permanent. 

 It deserves attention, that he found rosin, when dissol- 

 ved in nitric acid, and then thrown down by an alkali, 

 to acquire a smell resembling that of copal. 



When copal is dissolved in any volatile liquid, and 

 spread thin upon wood, metal, paper, &c. so that the 

 volatile menstruum may evaporate, the copal remains 

 perfectly transparent, and forms one of the most beau- 

 tiful and perfect varnishes that can well be conceived. 

 The varnish thus formed is called copal varnish, from 

 the chief ingredients in it. This varnish was firat disco- 

 vered in France, and was long known by the name of 

 vernis martin. The method of preparing it is concealed ;. 

 but different processes for dissolving copal in volatile 

 menstrua have been from time to time made public. 



According to the experiments of Thenard and Gay- 

 Lussac, copal is composed of 



Carbon 

 Oxygen . . 

 Hydrogen 



76.81 1 

 10.606 

 12.583 



100.000 



10. Lac. This is a substance deposited on different 

 species of trees in the East Indies, by an insect called 

 chermts Incca, constituting a kind of comb or nidus. It 

 has been imported into Europe, and extensively used 

 from time immemorial : but it is only of late years that 

 correct information concerning it has been obtained. 

 For what relates to the natural history of the insect, and 

 the mode of forming the lac, we are indebted to Mr 



