C H A P. IX.
WE have already mentioned, that, when any body is burnt in the center of a hollow sphere of ice and supplied with air at the temperature of zero (32°), the quantity of ice melted from the inside of the sphere becomes a measure of the relative quantities of caloric disengaged. Mr de la Place and I gave a description of the apparatus employed for this kind of experiment in the Memoirs of the Academy for 1780, p. 355.; and a description and plate of the same apparatus will be found in the third part of this work. With this apparatus, phosphorus, charcoal, and hydrogen gas, gave the following results:
One pound of phosphorus melted 100 libs. of ice.
One pound of charcoal melted 96 libs. 8 oz.
One pound of hydrogen gas melted 295 libs. 9 oz. 3½ gros.
As a concrete acid is formed by the combustion of phosphorus, it is probable that very little caloric remains in the acid, and, conse-
