Abstract

For some fifteen years in his chemistry lectures in Edinburgh, Joseph Black taught that phlogiston possesses absolute levity. It was not an aberration on Black's part: he justified the notion on experimental grounds. Moreover, the existence of a nongravitating substance capable of entering the composition of bodies raised intriguing possibilities for uniting physical and chemical phenomena. The doctrine became something of a tradition in Edinburgh, but was subject to growing criticism, particulary with the growth of pneumatic chemistry. By the early 1780s, Black found the hypothesis was no longer tenable and quietly dropped it, leaving a void in the explanation of weight relations in combustion which his students were quick to fill with Lavoisier's oxygen theory