The Maples. 237 



gives off an offensive odor in boiling. It crystalizes with difficulty, 

 and it is customary to use the last run, partly concentrated by boil- 

 ing, for making vinegar, by exposing it to fermentation. 



936. The flow of sap is much influenced by meteorological con- 

 ditions, and is best with freezing nights and thawing days, and in a 

 damp atmosphere. It will sometimes flow by night, and a run may 

 last two or three days, and then be suspended, from causes unknown, 

 until another freezing night. The sap flows in drops, at the rate of 

 from thirty to a hundred in a minute, and from three to four gal- 

 lons will make a pound of sugar. 



937. The holes bored in a maple tree will close up in two or three 

 years, and do not appear to injure the, growth of the trees. They 

 may be tapped annually from the time when they are ten or twelve 

 inches in diameter till they are seventy or eighty years old, and a 

 maple grove kept inclosed against cattle may be used perpetually 

 ibr sugar-making, the young trees coming on to replace those that 

 are cut at full maturity. 



938. The wood of the sugar maple is highly valued as a fuel and 

 for cabinet work, and varieties known as "birds-eye" are highly 

 valued for the making of veneers, affording some of the most beau- 

 tiful of the woods used in ornamental work. 



939. THE BLACK MAPLE (Acer nigruni) is commonly regarded as 

 only a variety of the A. saccharium, and is equally valuable for the 

 making of sugar, and its timber for all the uses to which the sugar- 

 maple is applied. 



940. THE SILVER-LEAF OR RIVER MAPLE (Acer dasycarpuni). 

 This and the next following species are often called "soft maples," 

 or " white maples," from the texture and color of the wood. They 

 bear fruit early in the season, and their seeds must be planted the 

 same year, and while still fresh. 



941. This species is planted extensively as a shade tree in the 

 Middle and Western States, and grows very rapidly, but the wood 

 being brittle, the trees are liable to injury by the winds. In rich 

 alluvial soils it grows to a large size ; -but the tree is not long-lived, 

 and its wood, although used for inside finishing and cabinet work, 

 soon perishes when exposed to the weather. 



942. The silver maple is less common in the South than the red 

 maple. In North Carolina it grows sometimes thirty or forty feet 

 high, and the sap is sometimes made into sugar, which has a su- 



