RESINS, MINERAL 701 



heated they melt more or less easily into a thick viscid liquid, and concrete, on cooling, 

 into a smooth shining mass, of a vitreous fracture, which occasionally flies off into 

 pieces, like Prince Kupert's drops, especially after being quickly cooled, and scratched 

 with a sharp point. They take fire by contact of an ignited body, and burn with a 

 bright flame, and the diffusion of much sooty smoke. When distilled by themselves 

 in close vessels, they afford carbonic acid and carburetted gases, empyreumatic oil of a 

 less disagreeable smell than that emitted by other such oils, a little acidulous water, 

 and a very little shining charcoal. See GAS, COAL. 



Resins are little acted upon by acids, except by the nitric, which converts them into 

 artificial tan. They combine readily with the alkalis and alkaline earths, and 

 form what were formerly reckoned soaps ; but the resins are not truly saponified ; they 

 rather represent the acid constituents themselves, and, as such, saturate the salifiable 



Every resin is a natural mixture of several other resins, as is tha case also with 

 oils ; one principle being soluble in cold alcohol, another in hot, a third in ether, a 

 fourth in oil of turpentine, a fifth in naphtha, &c. The soft resins, which retain a 

 certain portion of volatile oil, constitute what are called balsams. Certain other 

 balsams contain benzoic acid. The solid resins are, amber, anime, benzoin, colophony 

 (common rosin), copal, dammar, dragon's blood, elemi, guaiac, lac, resin of jalap, 

 labdanum, mastic, sandarach, storax, takamahac. 



1. The hard copal of India and Africa, especially Madagascar, is the product of the 

 Hymencea verrucosa. It is transparent and vitreous within, whatever may be its 

 appearance outside ; nearly colourless, or of a tawny yellow ; without taste or smell 

 in the cold, and almost as hard as amber, which it much resembles, but from which it 

 may be distinguished, 1st, by its melting and kindling at a candle-flame, and running 

 down in drops, while amber burns and swells up without flowing ; 2ndly, this hard 

 copal when blown out and still hot, exhales a smell like balsam copaiva or capivi ; 

 while amber exhales an unpleasant bituminous odour ; 3rdly, when moistened by 

 alcohol of 85 per cent., copal becomes sticky, and shows, after drying, a glazed opaque 

 surfa'ce, while amber is not affected by alcohol ; 4thly, the copal affords no succinic 

 acid, as amber does, on distillation. 



Ether, boiling hot, dissolves 39'17 per cent, of copal. 



Essence (spirits) of turpentine does not dissolve any of the copal, but it penetrates 

 and combines with it at a heat of 212 Fahr. 



2. Eesin of courbaril of Eio Janeiro, the English gum-anim6, and the semi-hard 

 copal of the French. It is characterised by forming, in alcohol, a bulky, tenacious, 

 elastic mass. It occurs in rounded tears, has a very pale glassy aspect, transparent 

 within, covered with a thin white powder, which becomes glutinous with alcohol. 

 Another variety is soft, and dissolves, for the most part, in alcohol; and a third 

 resembles the oriental copal so much as to indicate that they may both be produced 

 from the same tree. 100 parts of the oriental and the occidental anime yield 

 respectively the following residua : 



With alcohol With ether With essence 



Oriental . . . 6571 60'83 71 



Occidental . . . 43'53 27'50 7576 



The hard and soft copals possess the remarkable property in common of becoming 

 soluble in alcohol, after being oxygenated in the air. 



3. Dammar puti, or Dammar batu. This resin, soft at first, becomes eventually like 

 amber, and as hard. It is little soluble in alcohol and ether, but more so in essence 

 of turpentine. 



4. Aromatic dammar. This resin occurs in large orbicular masses. It is pretty 

 soluble in alcohol. Only small samples have hitherto been obtained. Of 100 parts, 

 3 are insoluble in alcohol, none in ether, and 93 in essence of turpentine. M. Guibourt 

 thinks that this resin comes from the Molucca isles. Its ready solubility in alcohol 

 and great hardness render it valuable for varnish-making. 



5. Slightly aromatic dammar leaves, after alcohol, 37 per cent. ; and after ether 17 

 per cent. ; and after essence, 87 per cent. 



6. Tender and friable dammar selan. This resin occurs in considerable quantity 

 in commerce (at Paris). It is in round or oblong tears, vitreous, nearly colourless, 

 and transparent within, dull whitish on the surfaces. It exhales an agreeable odour 

 of olibanum, or mastic, when it is heated. It crackles with the heat of the hand, like 

 roll-sulphur. It becomes fluid in boiling water, but brittle when cooled again. It 

 sparkles and burns at the flame of a candle ; but this being the effect of a volatile oil, 

 the combustion soon ceases. Guibourt. 



RESIN'S, MINERAXi. Petroleum, bitumen, asphalt, amber, and other mineral 

 hydrocarbons are so called. See descriptions under the respective names. 



