326 CHEMISTEY. 



445. Unsafe Kerosene. The cheapness of kerosene oil, the 

 brilliancy of its light, the freedom of its flame from smoke 

 when burned in suitable lamps, makes it universally used 

 for illuminating purposes. Unfortunately many accidents 

 occur by explosion of lamps, but this is only because the 

 kerosene oil contains too much of the lighter oils, benzine 

 and naphtha. This makes the oil too readily inflammable, 

 for the vapors of the lighter oils are driven out by heating 

 (as when a lamp is burning), and these mixed with the oxy- 

 gen of the air form a dangerous explosive mixture. There 

 is a law requiring manufacturers to keep kerosene oil free 

 from these lighter oils ; but since the latter are not worth 

 so much, the wicked avarice of some manufacturers causes 

 them to break the law and run the risk of detection. 

 Hence so many fatal accidents. 



446. White Rotten Wood. There is a decay of wood in 

 the hollow trunks of trees which produces a singular sub- 

 stance when there is no opening in the trunk to permit the 

 access of air. This substance differs from that which or- 

 dinarily results from the decay of wood, very much as a 

 hydrate does from an anhydrous oxide. For example, it is 

 as iron rust differs from common oxide of iron. This rotten 

 wood can be prepared artificially. If you put some moist- 

 ened saw-dust into a closed vessel in summer, and let it 

 stand for some months, you will find it converted into a 

 white friable substance, which is perfectly dry because the 

 water has chemically united with it. White rotten wood 

 is sometimes luminous from some chemical change which is 

 going on in it. 



447. Chlorophyll. This substance, leaf-green, giving the 

 green color to leaves and twigs and stalks, is one of the 

 most widely diffused of vegetable substances. It is not one 

 single substance, but is a mixture of several coloring sub- 

 stances, the character of. which- has not been fully ascer- 



