Experiments on the different Kinds of Coal. 287 



air, at a temperature of from 12^ to 15° of Reaumur. The same 

 species of matter was, on the one hand, submitted to a very ra- 

 pid carbonization, for which, from the commencement of the 

 distillation, an incandescent heat was employed ; and, on the 

 other hand, to a temperature which was made to rise very slow- 

 ly to this point. The contents in ashes were carefully deter- 

 mined, by means of the incineration of charcoal under the muf- 

 fle of an assay furnace. The weight of the ashes is deducted 

 from that of the charcoal in the following table. 



It is sufficient to cast a glance upon this table to observe a 

 general result, which is as follows: — Whatever difference the 

 vegetable fibres of graminea?, ferns, and different species of wood, 

 present to the eye, these matters all afford nearly equal quanti- 

 ties of charcoal by dry distillation. The differences which 

 are observed here and there, may arise from the impossibility of 



* Instead of Old Birch, say Birch-wood, which, for upwards of 100 

 years, had been used as a support in a mine, and was still in good preserva- 

 tion. 



