USEFUL PROJECTS. 



661 



air, and submitted to a strong red 

 heat, in a black lead crucible for 

 twenty minutes, is in a good state 

 for the purpose. 



The bottle, when full, may be 

 exposed, corked, to the radiant 

 heat of a fire, till some of the 

 pieces of phosphorus haveassumed 

 an orange tint ; it will then be 

 ready for immediate use. But 



the heating is not absolutely ne- 

 cessary if the bottle is not wanted 

 for immediate use, and it will 

 continue longer in a serviceable 

 state. 



It is almost superfluous to ob- 

 serve, in using the bottle, the 

 mouth should be closed with the 

 finger as soon as the match is 

 withdrawn. 



