1096 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Tlio further treatment of tho resinous solution vanes with the 

 intended application. If a very pure resin be desired it is advisable 

 to let the solution stand in a cool place for weeks, in order to allow 

 any fatty matter to separate out. Tho solution is then filtered and 

 concentrated by distillation. If only required as a scaling varnish, 

 concentration may be proceeded with at once. According to tho 

 author, the resin thus obtained possesses every quality desirable in a 

 mounting or inclosing medium ; in toughness, hardness, and perma- 

 nency it is unequalled, and while quite colourless and transparent, 

 easily takes up anilin dyes of any desired colour. 



When used for mounting the shellac resin is dissolved in iso- 

 butyric-alcohol, as ordinary spirit is found in practice to bo too 

 hygroscopic. 



2. Storax. — Fluid storax as it occurs in commerce is a thick, 

 viscid opaque mass, with an agreeable smell and a mouse-grey colour. 

 The opacity is due to numerous drops of water and solid impurities 

 which are removed by dissolving the balsam in three or four times its 

 weight of ether, and leaving the solution in contact with calcium 

 chloride for some days. By filtration and distillation over a water- 

 bath pure fluid storax is obtained. The following bodies are found 

 therein : — (1) styrol ; (2) cinnamic acid ; (3) ethyl-vanillin ; (4) 

 styracin ; (5) cinnamic methylate ; (6) cinnamic cthyl-propylate ; 

 (7) two bodies of unknown constitution, a and j3 storesin ; (8) a resin. 

 The last five bodies may be considered tho actual constituents, as 

 the first three only appear in very small quantities, and after being 

 kept for a long time, constituents 5 and 6 disappear ; but this disap- 

 pearance is unaccompanied by any diminution in volume or weight. 

 The reason of this the author afterwards explains. In order to sepa- 

 rate the fluid from the solid constituents, the storax is treated with 

 petroleum-ether (boiling point 45°-50 : ' C). The solid residuum 

 is placed in glass bulbs, and petroleum-benzin poured over. After 

 being well shaken up it is allowed to stand until the solution sepa- 

 rates into two layers, when the colourless solution is poured off. This 

 treatment is repeated thrice, and then by distilling off the petroleum- 

 benzin, a colourless oil of a high refractive index is obtained. 



When dry the resin becomes quite hard, but is still brown, and to 

 deprive it of this colour it is treated with about five times its weight 

 of pure benzol, and then petroleum-benzin added slowly until the 

 fluid becomes the colour of hock. Having settled, it is filtered, and 

 the solvent distilled off from the filtrate. As an imbedding medium 

 the resulting substance is faultless. Its refractive coefficient is that 

 given by Van Heurck. It is of a dark yellow colour in bulk, but 

 colourless in thin layers. When cold it is perfectly solid, and 

 although its melting-point is lower than that of Canada balsam, it is 

 quite brittle when exposed to the hottest sun. 



This medium, for which the name of styresin is proposed, is dis- 

 solved for use in turpentine oil and treated exactly like Canada 

 balsam. 



The cause of the spontaneous hardening of storax after standing 

 for many years, is associated with the presence of the pure cinnamic 



