32 PRACTICAL TREE REPAIR 



kind of asphaltum in benzine and has no value 

 as a wound dressing. It does not spread thickly, 

 dries brittle, and is rapidly dissolved by water. 

 Pine tar, or pitch, is rather expensive, not very 

 convenient to handle, and in no way superior to 

 coal tar. A special warning should be sounded 

 against those forms of tar which are hard and 

 brittle at ordinary temperatures and have to be 

 melted to be applied. Such are sure to chip off 

 and be unsatisfactory. 



Coal tar is the material intended wherever the 

 word tar is used in this book. It is one of the 

 residuums from the distillation of bituminous coal 

 in the process of making coal gas. Coal tar is 

 sometimes called gas tar, but that expression ap- 

 plies also to a by-product of the manufacture of 

 water-gas out of petroleum. That sort of tar 

 has no preservative value and should not be used 

 on trees. In buying tar for that purpose the only 

 safe way is to get it from, or trace it from, a gas 

 works producing gas from coal. In case of doubt 

 have the dealer sign a guarantee that the tar is 

 wholly the product of the destructive distillation 

 of bituminous coal. 



Tar makes a very good dressing if it is carefully 

 applied and if not too much is asked of it. It is 

 at its best when heavy applications are made in 

 winter, when it usually needs to be heated, to dry 

 and not too large surfaces. It is absorbed by a 



