Mr. Faraday on the Liquefaction of Gases. 233 



experiments of Guyton de Morvean, Ann. de Chimie. xxix. 291, 

 297. Thomson states the result of liquefaction at a temperature 

 of —45°, without referring to the doubt, that Morveau himself 

 raises, respecting the presence of water in the gas ; but Murray, 

 Henry, and Thenard, in their staiements notice its probable pre- 

 sence. Morveau's experiment was made in the following manner: 

 a glass retort was charged with the usual mixture of muriate of 

 ammonia, and quick lime, the former material being sublimed, 

 and the latter carefully made from white marble, so as to exclude 

 water as much as possible. The beak of the retort was then 

 adapted to an apparatus consisting of two balloons, and two flasks 

 successively connected together, and luted by fat lute. The bal- 

 loons were empty, the first flask contained mercury, the second, 

 water. Heat was then applied to the retort, and the first globe 

 cooled to — 21.25°C, aqueous vapours soon rose, which condensed 

 as water in the neck of the retort, and as ice in the first balloon. 

 Continuing the heat, ammoniacal gas was disengaged, and it es- 

 caped by the last flask containing water, without any thing being 

 perceived in the second balloon. This balloon was then cooled to 

 — 43.25°C, and then drops of a fluid lined its interior, and ulti- 

 mately united at the bottom of the vessel. When the thermome- 

 ter in the cooling mixture stood at —36. 25°C, the fluid already 

 deposited preserved its state, but no further portions were added 

 to it; reducing the temperature again to — 41°C, and hastening 

 the disengagement of ammoniacal gas, the liquid in the second 

 balloon augmented in volume. Very little gas escaped from the 

 last flask, and the pressure inwards was such as to force the oil 

 of the lute into the balloon where it congealed. Finally, the ap- 

 paratus was left to regain the temperature of the atmosphere, and 

 as it approached to it, the liquid of the second balloon became 

 gaseous. The fluid in the first balloon became liquid, as soon as 

 the temperature had reached — 21.25 C C. 



M. Morveau remarks on this experiment, that it appears certain 

 that ammoniacal gas made as dry as it can be, by passing into a 

 vessel in which water would be frozen, and reduced to a tempera- 

 ture of — 21°C, condenses into a liquid at the temperature of —48° 

 C, and resumes its clastic form again as the temperature is raised ; 



