Chap. 5%] Baffams. .51 



expo fore to the air they become thick, and in procefs 

 Of time affurhe the character of refin. Needle- 

 fhaped cryftals are depofited fimilar to thofe afforded 

 by camphor when fublimed. Geoffrey the younger 

 obferved them in the effential oils of motherwort, 

 marjorum, and of turpentine. The fame chemift ob- 

 ferves, that their fmell is fimilar to that of camphor. 



Effential oils combine very readily with fulphur, 

 and form compounds called balfams of fulphur, in 

 which the fulphur is fo far changed that it cannot be 

 recovered. 



V. The proper vegetable BALSAMS are oily aro- 

 matic fubftances, imperfectly fluid, obtained by inci- 

 cifions made in certain trees. The word balfam has 

 been ufed in a very extenfive fenfe, to denote a variety 

 of vegetable fubftances, which agree in confidence, 

 though differing very widely in their nature and pro- 

 perties. This denomination, however, is more pro- 

 perly confined to fuch refmous matters as poifefs a 

 fragrant fmellj and more efpecially contain acid, odo- 

 rant, and concrete falts, which may be extracted by 

 decoction or fublimation ; fuch as benzoin, balfam 

 of Tolu, and ftorax. 



VI. CAMPHOR is a peculiar vegetable fubftance, of 

 a ftrong fmell and tafte, which refembles efTential oils 

 in fome of its properties* and differs from them in 

 others. It is much more volatile than the effential oils; 

 with the moft gentle heat it ftiblimes and chryftalizes 

 in hexagonal laminae attached to a middle ftem. By 

 a fudden heat it melts before it rifes. Water does 

 not diilblve it j but it is plentifully foluble in fpirits of 

 wine, aether, and concentrated acids, from the two 

 former of which it is feparated by the addition of water 

 without alteration. Fixed and volatile oils diflblve 



I 2 camphor 



