284 Chemical Examination, ^'■c. 



vegetable bodies, containing a large proportion of resin, are known 

 to resist decomposition for ages, the combustibility of the bark and 

 its enduring qualities when exposed to heat and moisture, are un- 

 questionably due to its resinous ingredient. 



The resin constitutes a great proportion of the bark ; so great a 

 proportion indeed, that when heated in close vessels, the whole mass 

 appears to melt. It is singular that the resin, when so abundant, 

 never manifests itself by a spontaneous exudation from the tree. 



In the course of some of the experiments detailed above, 1 spread 

 a portion of the resin upon a paper, and placed it upon a warm stove, 

 with a view to dry it effectually. In this situation it was accidentally 

 subjected to so high a temperature, that a portion of the resin began 

 to melt. Attracted by the odor with which the room was filled, I 

 immediately removed it from the stove, and was surprised to find that 

 the whole surface of the resin was covered with brilliant acicular 

 crystals, radiating from every elevated point, and crossing each other 

 at every possible angle. This crystalline matter resembled benzoic 

 acid so closely that at first I supposed it was that substance, and con- 

 sequently, the resin containing it belonged to the class of balsams. 

 A subsequent examination, however, convinced me that that supposi- 

 tion was erroneous although it was not decisive of the real nature of 

 the substance. 



It is extremely difficult to obtain this body in large quantities, and 

 no means that I have applied, have proved more effectual than those 

 by which it was first procured. It possessed the following properties : 



It experienced no change by exposure to the atmosphere for weeks. 

 It was destitute of taste, and, at common temperatures, of smell. 

 When gently heated, it afforded the peculiar odor of the resin. 



The copious vapors, arising from it, could be inhaled without any 

 of that irritation of the respiratory organs which the vapor of benzoic 

 acid occasions. It was absolutely insoluble in cold water, and very 

 sparingly so, if at all, in hot. It combined instantly with alcohol and 

 ether. Digested with dilute muriatic and nitric acid«, imperfectly 

 crystallized compounds were formed, which possessed a strong bitter 

 taste. 



If this examination be too imperfect to authorise any decision upon 

 the chemical nature of this substance, it is, I think, nevertheless con- 

 clusive as to those properties which distinguish it from the benzoic 

 acid, which it so much resembles in appearance. 



