VEGETABLE WAX. 143 



this way the whole circumference of the tree finally presents a series 

 of notches, so that a tree will continue to yield turpentine during a 

 period of sixty years. The turpentine which exudes from the 

 notches is collected in a hole dug in the ground. 



Crude turpentine always contains a quantity of intermixed foreign 

 matters, earth, stones, leaves, &c. It is purified by being melted, and 

 filtered hot through a bed of straw. By distillation it is separated into 

 essential oil, which is condensed in the receiver, and colophony, or 

 rosin, which remains in the still. From 250 lbs. of turpentine 30 lbs. 

 of essence and 220 lbs. of rosin are generally obtained. 



Copal is the produce of a tree which is somewhat common in 

 Madagascar, and which M. Perrotet has determined to be the Hy- 

 menaa verrucosa. The balsam or sap which exudes from the bark 

 solidifies by contact with the air, and the resin is gathered in the 

 state in which it is met with in commerce. 



CAOUTCHOUC. 



The caoutchouc which we have mentioned as forming a constituent 

 in the sap of certain trees possesses some properties which assimi- 

 late it with the resins. Thus pure ether, free from alcohol, dis- 

 solves it. The greater number of the essential oils also dissolve it, 

 particularly when hot. It is a solution of Indian rubber in rectified 

 coal-tar oil or naphtha, which is now used so extensively for making 

 stuflfs water-proof. According to Faraday pure caoutchouc is 

 composed of : 



Carbon 87.2 



Hydrogen 12.8 



 100 



VEGETABLE WAX. 



Some plants produce a considerable quantity of a substance which 

 bears a great resemblance to beeswax, and which in some of its 

 properties approaches fatty bodies. Proust discovered that vegeta- 

 ble wax formed part of the green fecula of a great number of vege- 

 tables. In the common cabbage it occurs in large quantity. It is 

 often met with forming a varnish on the surface of leaves, fruit, and 

 barks ; the substance, however, is far from being identical ; it al- 

 most always results from the combination of several distinct princi- 

 ples which have not yet been sufficiently studied, but among which 

 there are obviously some true fatty substances, that is to say, bodies 

 capable of saponification, and matters analogous to the resins. I 

 shall here mention a few of the vegetable waxes which are best 

 known. 



Wax of the palm. This is the product of the Ceroxylon andicola, 

 which is very abundant on the central Cordillera of New Grenada. 

 I believe that I met with the Lower limit of the ceroxylon upon the 

 holders of the torrent of Tochecito, at the height of 7500 feet above 

 the level of the sea, and I followed it to an absolute elevation of 

 about 8500 feet. The extreme mean temperatures comprised be- 



