1823.] of several Gases into Liquids. 95 



boiled, giving off ammoniacal gas, which condensed at the 

 opposite end into a liquid. 



Liquid ammonia thus obtained was colourless, transparent, 

 and very fluid. Its refractive power surpassed that of any 

 other of the fluids described, and that also of water itself. 

 From the way in which it was obtained, it was evidently as 

 free from water as ammonia in any state could be. When the 

 chloride of silver is allowed to cool, the ammonia immediately 

 returns to it, combining with it, and producing the original 

 compound. During this action a curious combination of effects 

 takes place : as the chloride absorbs the ammonia, heat is pro- 

 duced, the temperature rising up nearly to 100; whilst a few 

 inches off, at the opposite end of the tube, considerable cold 

 is produced by the evaporation of the fluid. When the whole 

 is retained at the temperature of 60, the ammonia boils till it 

 is dissipated and re-combined. The pressure of the vapour 

 of ammonia is equal to about 6*5 atmospheres at 50. Its spe- 

 cific gravity was 0*76. 



Muriatic Acid. When made from pure muriate of ammonia 

 and sulphuric acid, liquid muriatic acid is obtained colourless, 

 as Sir Humphry Davy had anticipated. Its refractive power 

 is greater than that of nitrous oxide, but less than that of 

 water ; it is nearly equal to that of carbonic acid. The pres- 

 sure of its vapour at the temperature of 50 is equal to about 

 40 atmospheres. 



Chlorine. The refractive power of fluid chlorine is rather 

 less than that of water. The pressure of its vapour at 60 is 

 nearly equal to 4 atmospheres. 



Attempts have been made to obtain hydrogen, oxygen, fluo- 

 boracic, fluosilicic, and phosphuretted hydrogen gases in the 

 liquid state ; but though all of them have been subjected to 

 great pressure, they have as yet resisted condensation. The 

 difficulty with regard to fluoboric gas consists probably in its 

 affinity for sulphuric acid, which, as Dr. Davy has shown, is so 

 great as to raise the sulphuric acid with it in vapour. The 

 experiments will, however, be continued on these and other 

 gases, in the hope that some of them, at least, will ultimately 

 condense. 



