456 On phlogiston. 



The fecond obiedtion of Dr. Prieftley, to the new theory 

 of chemiftry is, that when a metal is reduced to a calx, 

 it throws out fomething which forms phlogifticated air. 

 He fays, that when the focus of a burning lens, is thrown 

 upon iron confined in atmofpheric air, the dephlogifticat- 

 ed air is not merely feparated from the phlogifticated air, 

 but that the phlogifton from the iron, unites with the de- 

 phlogifticated air and forms azotic gas. 



In order to fee if this affertion was juft, the focus of the 

 burning lens belonging to our fociety, which is eleven inches 

 in diameter, was thrown upon ninety grains of the filings 

 of bar iron, filed for the purpofe, confined in thirty-two 

 ounce meafures of oxygenous gas, which had been well 

 walhed in lime water, and which was fo pure, that nearly 

 the whole of it was devoured by the teft of nitrous air. 

 Twenty-eight ounce meafures of the pure air were abforbed 

 by the iron, which was reduced to a calx. 



The quantity of carbonic acid produced, which was 

 formed by a fmall quantity of coal, which all iron of com- 

 merce contains, uniting to a part of the pure air, amount- 

 ed to one ounce meafure. 



When the fixed air was abforbed by wafliing it in lime 

 water, the remaining air was in no manner injured. 



The focus of the lens was likewife thrown, upon fixty 

 grains of the filings of copper, confined in iixteen ounce 

 meafures of oxygenous gas. Twelve ounce meafures of 

 the pure air were abforbed by the metal, which was con- 

 verted into a calx. No carbonic acid or azotic gas was 

 formed, and the remaining air was perfedlly pure. Thefe 

 experiments prove, contrary to what has been faid by Dr. 

 Prieftley, that when a metal, containing no foreign fub- 

 ftance, is calcined in oxygenous gas, the pure air only is 

 imbibed, no fubftance is emitted from the metal, and no 

 azotic gas is formed. 



Section 



