Note 22 — Chapter III

This, as previously remarked, had already been noticed. In Maquer’s Élémens de Chymie-pratique, published in 1752, a work which ran through many editions, we read (p. 307): “There happens during all these calcinations, and especially in that of lead, a very strange phenomenon for which it is very difficult to assign a reason. It is that those bodies, which lose no small proportion of their substance, whether by the dissipation of phlogiston, or because part of the metal is exhaled as vapour, yield calces increased in weight after calcination; and this increase is by no means inconsiderable.... Physicists and chemists have devised many ingenious systems to account for this phenomenon, but no one of them is absolutely satisfactory. As no well-established theory has been devised, we shall not undertake to attempt an explanation of this singular fact.”