"All ['s] calculation is founded on the supposition that the calcination of metals is the result of the loss of phlogiston. But what I have been saying (...well known by now) is that this loss of phlogiston, even in the presence of metals is, according to me, nothing but pure supposition. What is more real, what can be known, by the balance and direct measurements, is that in all metallic s, whether made in the dry or humid way, whether... with the aid of air or water, or by means of acids, there is an augmentation of weight of the metal... due to the addition of vital air, or specifically the oxygen principle."