Bark of the White Birch, 283 



generally be found in a state of decay while the bark, which covers 

 them, is entirely sound. The bark may easily be collected in cylin- 

 drical pieces, by shaking out its rotten contents. These cylinders 

 are frequently converted into baskets and other articles, and very 

 often employed for kindling materials, and for torches, in the noctur- 

 nal excursions of youthful anglers. Recollecting these facts,' I was 

 induced to undertake a few experiments, with a view of ascertaining 

 to what principle the bark owes its inflammability, and its power to 

 resist the ordinary agents of decay. 



A portion of the bark, chipped fine, was acted upon by boiling 

 water. The water separated neither volatile oil nor wax. It con- 

 tained some extractive matter and tannin. Upon the same portion 

 of bark, highly rectified alcohol was kept in gentle ebullition a long 

 time. The alcohol was decanted off and suffered to cool, and a very 

 copious curdly precipitate formed. When the whole of die alcohol 

 was evaporated, a granular substance was obtained, which resembled, 

 in appearance, the lighter varieties of muscovado sugar, or more 

 closely, the sugar from starch. This substance possessed the follow- 

 ing properties : It was extremely combustible, and when thrown upon 

 hot coals, it diffused throughout the apartment, a peculiar and very 

 agreeable odor. It fused at a temperature of 454°.'^ After fusion, 

 it resembled the darker varieties of the resin from pine. By friction 

 it exhibited negative electricity. It was insoluble in water, but it 

 readily dissolved in alcohol and ether. With several of the essential 

 oils it combined, but with much greater difficulty than common resin. 

 With the oil of turpentine, however, it very readily formed a clear 

 solution. It combined with solution of potassa, and from this alka- 

 line solvent it was separated by the addition of an acid. 



These characters entitle this substance to a rank among the resins, 

 and at the same time, they are sufficiently distinctive of a peculiar 

 variety. The high temperature at which it fuses, and the odor afford- 

 ed when thrown upon hot coals, are characteristic of no similar body. 

 The bark, when acted upon by repeated portions of boiling alcohol, 

 becomes no more combustible than ordinary woody fibre, and as all 



* A small quantity of the birch resin was put into a glass tube, and a like quan- 

 tity of common resin in another. The tubes, together with a thermometer, were 

 placed in oil, which was heated over a furnace. The temperatures at which the 

 resins began to melt was noted. Common resin, under these circumstances, melted 

 at 218° Faren. 



