BODIES GENERALLY EXISTING AS GASES. 



163 



The following are some results of pressure, all that I could obtain with the liquid 

 in my possession ; for, as the liquid is light and the gas heavy, the former rapidly 

 disappears in producing the latter. They make no pretensions to accuracy, and are 

 given only for general information. 



The preceding are, as far as I am aware, new results of the liquefaction and solidi- 

 fication of gases. I will now briefly add such other information respecting solidifi- 

 cation, pressure, &c., as I have obtained with gaseous bodies previously condensed. 

 As to pressure, considerable irregularity often occurred, which I cannot always refer 

 to its true cause; sometimes a little of the compressed gas would creep by the mer- 

 cury in the gauge, and increase the volume of inclosed air ; and this varied with 

 different substances, probably by some tendency which the glass had to favour the 

 condensation of one (by something analogous to hygrometric action) more than 

 another. But even when the mercury returned to its place in the gauge, there were 

 anomalies which seemed to imply, that a substance, supposed to be one, might be a 

 mixture of two or more. It is, of course, essential that the gauge be preserved at the 

 same temperature throughout the observations. 



Muriatic acid. — This substance did not freeze at the lowest temperature to which 

 I could attain. Liquid muriatic acid dissolves bitumen ; the solution, liberated from 

 pressure, boils, giving off muriatic acid vapour, and the bitumen is left in a solid 

 frothy state, and probably altered, in some degree, chemically. The acid unites 

 with and softens the resinous cap cement, but leaves it when the pressure is dimi- 

 nished. The following are certain pressures and temperatures which, I believe, are 

 not vei-y far from truth ; the marked numbers are from experiment. 



The result formerly obtained* was forty atmospheres at the temperature of 50° Fahr. 



* Philosophical Transactions, 1823, p. 198. 

 v2 . 



