fcX AIR FROJ^ EINEFY CINDER AND CHARCOAL. 



Mr. Cruickfhank's obfervation of the union of the oxigen in 

 the dephlogifticated marine acid air with inflammable air in the 

 common temperature of the atmofphere, is extremely curious 

 but I do not fee that any thing more can be inferred from 

 it, than from the more rapid union of the fame principles 

 when inflammable and dephlogifticated air are fired toge- 

 ther. 



Ouifkfcank^ Mr * CruIckfllank favs > P- 201 » tnat " the oxigen in the finery 

 theory of there- <c cinder, uniting with the carbon in the charcoal, forms fixed 

 duftion of finery « a j r . an( j that the metal being in the fame procefs revived, 

 coa j # M decompofes this fixed air, when it becomes again to a cer? 



" tain degree oxigenated." But why (hould not the finery 

 cinder retain a part of its oxigen, rather than firft part with it, 

 and then take it again ? Befides, it is not true that after this 

 procefs the iron is in any degree oxigenated, for it is com- 

 pletely revived, being perfect iron ; and that any fixed air is 

 either formed or decompofed in this procefs is altogether con- 

 jectural, and for the reafons that I have given cannot be ad- 

 mitted. For though it might be poflible for oxigen in the finery 

 cinder (fuppofing it to contain that principle) to be extracted 

 from it by its affinity with the carbon in the charcoal, and that 

 nothing (hould enter in its place, the iron thus revived could 

 not decompofe the fixed air that would be formed by their 

 union. 



Not doubting but that Mr. Cruickftiank will give a candid 

 attention to thefe obfervations, 



I am, 



Dear Sir, 



Your's fincerely, 



J. PRIESTLEY, 



XII. Defcription 



