obtained in the distillation of Wood, Effr. 5 



stopped when the oily matter begins to acquire a brown colour, and 

 when the production of acetic acid is less perceptible, the matter in 

 the retort will be found when cold, to have assumed a solid con- 

 sistence. In this state it resembles either pitch or asphaltum, accord- 

 ing to the degree of heat it has undergone after it became capable 

 of solidifying. 



I will describe this substance as it appears when it first becomes 

 solid, the reason of which will soon be apparent. 



Previously to its arriving at this state, it bears a considerable 

 resemblance to maltha, being of a consistence intermediate between 

 that of petroleum and asphaltum-, but 1 did not completely examine 

 its chemical properties in this condition because they appeared not 

 to differ from v/hat might be expected, and its history will be 

 sufficiently full without it. In the solid state it is brilliant and 

 shining and breaks with a conchoidal fracture and some external 

 resemblance to obsidian. It has a pungent burning taste and the 

 well known smell of wood smoke. It is heavier than the specimen 

 of asphaltum with which I compared it, having a specific gravity 

 of 1.254, while that of the asphaltum was 1.202. It is fusible and 

 readily inflammable, burning with a white flame. It is electric 

 and exhibits the same electricity as the resinous bodies. When 

 heated in an open vessel, it smokes, and if kept in fusion till it 

 ceases to smoke, it at length ceases to be fusible and is ultimately 

 converted into a coal. During this progress it becomes more bril- 

 liant and less fusible, its fracture also from conchoidal becomes more 

 splintery, and it puts on the appearance of asphaltum so accurately 

 that the eye cannot detect the diflference. Its specific gravity also 

 diminishes, and its chemical properties vary in the way I am now 

 about to detail. 



I have described the perfect solubility of the tar in alcohol. The 



