THE KINDLING TEMPERATURE 



181 



Experiment. To find out if all substances take fire at the same temperature. 



Materials: Tin plate or sheet iron. Sulphur. Phosphorus. Wood. 

 Ring stand. Clamp. Burner. 



Method: Support the sheet iron horizontally with a clamp attached to 

 ring stand. Place a few short pieces of wood (broken match stems) 

 on the middle of the 

 iron plate, and two 

 inches distant from 

 this place on one 

 side a lump of sul- 

 phur the size of a 

 pea, and on the other 

 side a piece of phos- 

 phorus the size of a 

 rice grain. (Do not 

 handle phosphorus 

 with the bare hands 

 and always cut it 

 under water.) Place a low flame under the middle of the iron. 

 The iron distributes the heat so quickly that we may assume that 

 all the materials are being warmed equally at the same time. Each 

 time one burns we may turn the heat on a little stronger. 



Observations: Note the appearance of smoke, the melting of the sub- 

 stances, and the order of taking fire. 



Conclusion: The temperature at which a substance takes fire is known 

 as the kindling temperature. What does this experiment show you 

 in regard to kindling temperatures of sulphur, phosphorus, and 

 wood? 



The kindling temperature. It is evident that different 

 substances take fire at different intensities of heat. The 

 intensity or degree of heat is called temperature. In the 

 experiment, we found that the phosphorus burns first, then 

 the sulphur, while a much higher flame is necessary to 

 make the wood burn. Evidently some substances kindle 

 at a much lower intensity of heat than others. If we now 

 use a thermometer, an instrument used for detecting dif- 

 ferent intensities of heat, or temperatures, we can find the 

 exact kindling temperatures of many substances. 



