SPECIMENS OF FOSSIL WOODS IN NATAL MUSEUM. O / 



changes ■which the wood undergoes as it is being transformed 

 into the remarkable jet-like substance. The chemical changes 

 which take place require a detailed investigation by a quali- 

 fied chemist. 



In the following table the percentages of carbon, hydrogen 

 and oxygen in a number of different substances and minerals 

 are given : 



Material.! 



Carbon. Hydrogen, Oxygen/ 



It will be seen that the composition of the organic and 

 volatile matter of the fossil wood and jet-like mineral com- 

 pared with that of bituminous and cannel coal is characterised 

 b}'^ an excess of hydrogen and oxygen, and compared with 

 that of the oxygenated carbohydrates. Succinite and 

 Torbanite, it shows an excess of oxygen. 



The excess of oxygen is probably connected with the con- 

 ditions under which the transformation proceeded, since the 

 presence of the oxygen of the air would permit a large portion 

 of the oxygen of the original organic matter to remain. 



The yellowish-red or brown resin-like substance at first 

 filling the cavities of the wood and ultimately taking the 



^ This table is mostly compiled from Dana's ' Mineralogy.' 1889. 

 - Any small amount of nitrogen that may be present is included in 

 the figiu-es of this column. 

 ^ Excluding the inorganic matter and moisture. 



