252 ECONOMIC BOTANY. 



etc., of various Coniferous trees. It is used extensively for 

 preserving cordage and woods from the effects of the 

 atmosphere. From tar is produced pitch, oil of tar, 

 creosote, etc, 



218. Mecca Balsam, or Balm of Gilead, is obtained 

 from a small Arabian tree called Balsamodendron gileor 

 dense, of the' Myrrh family {BurseracecB). The tree has 

 slender branches, small bright-green leaves, and small white 

 flowers with four petals. The fruit is an oval berry. The 

 best quality of the balsam flows from incisions made in the 

 twigs ; but this is scarce, as only about sixty drops a day 

 exude. The common mode of obtaining it is by boiling 

 the twigs in water. Its taste is bitter, and the odor is that 

 of turpentine, but suggestive of lemon and Forget-me-not. 

 It has the consistency of pine turpentine ; at first thinner, 

 afterwards thicker. It is often of a brownish-red color, 

 and somewhat cloudy ; the best is yellowish, and has a 

 pleasant aromatic odor. Under the microscope it is clear, 

 and shows no solid impurities. Potato starch in it is not 

 visible; but if olive-oil or castor-oil is added the starch 

 grains can be seen. This, therefore, serves as a means for 

 detecting these adulterations. It is used by the Turks in 

 odoriferous ointments and cosmetics. It is employed in 

 the manufacture of perfumery and in medicine. Myrrh, 

 a gum-resin very similar to the last, and said to be one of 

 the oldest medicinal articles known, is from another small 

 tree of Arabia belonging to the same genus (B. myrrha). 

 It is semi-transparent, reddish or yellowish. The taste is 

 aromatic and bitter, the odor characteristic and pleasant. 

 In medicine it is used as a stomachic and tonic. 



219, The Copaiba Balsam is from Copaifera muUijuga, 

 a large leguminous tree (family LeguminoncB) of Brazil 



