duce the temperature to the freezing-point, and the liquid will be converted into ice.
In 1755, Dr. Cullen discovered that removing the pressure of air facilitated evaporation to a degree which enabled him to freeze water even in summer.
In 1777, Mr. Nairne discovered that introducing sulphuric acid into an exhausted receiver absorbed an aqueous vapor from and thereby dried rarefied air; and by an arrangement on these principles, in 1810, by which he got rid of the vapor that rose from thtions, the entrances to the egg-chambers showing in the upper view at c′. The upper chambers are connected.
The ancient Egyptian incubators are referred to by Aristotle, Diodorus Siculus, and Flavius Vopiscus.
Bonnemain's incubator B (A. D. 1777) is heated by hot water.
a is the boiler; b, a building for holding the eggs on shelves; c, a coop for holding the chickens; d, tube for circulating the hot water; e, a supply funnel; f, a safety tube.
The hot water rises from the boiler into tu