OAK BARK. 179 



if put into hot-beds properly prepared, it retains a 

 moderate heat for three or four months. When it 

 becomes useless for the hot-house, it can still be used 

 with advantage as manure for some kinds of lands. 



It was formerly supposed by English tanners, that 

 the tanning principle resided in oak bark alone, but 

 how or why its use was beneficial in the preparation 

 of skins, was a mystery for which no one attempted to 

 account. The scarcity of this bark, however, and its 

 consequent high price, at length led to the investiga- 

 tion of its properties, and of its peculiar virtue in 

 tanning, in the hope that similar qualities might be 

 found to reside in other substances. 



Oak Quercus pcduncalata. ; 



Of every pursuit which has for its object the im- 

 provement of our domestic arts and manufactures, 

 and the advancement of our colonies, the Society for 

 the Encouragement of Arts, &c. has always been the 

 zealous promoter, and accordingly we find it so 

 early as 1765 offering premiums to any who should 



