198 
Mr. Faraday on the condensation , &c. 
Muriatic acid , 
When made from pure muriate of ammonia and sulphuric 
acid, liquid muriatic acid is obtained colourless, as Sir Hum- 
phry 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 pressure of its 
vapour at the temperature of 50°, is equal to about 40 at- 
mospheres. 
Chlorine. 
The refractive power of fluid chlorine is rather less than 
that of water. The pressure of its vapour at 6o° is nearly 
equal to 4 atmospheres. 
Attempts have been made to obtain hydrogen, oxygen, 
fluoboracic, 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 hopes that some of them, at 
least, will ultimately condense. 
