Compression of Air and other Gases. 233 



From this table, it appears that the differences are very in- 

 considerable, and vary on one side and anothei, till the pres- 

 sure amounts to 2.3 atmospheres, when they become greater, 

 and go on increasing. At a pressure of 3.2689, a little above 

 that represented in the table, the humidity becomes visible, 

 and beyond this the contraction takes place rapidly. Before 

 this term, there is, perhaps, a feeble liquefaction at the con- 

 tact of the gases with the sides of the cylinder, and at the 

 surface of the mercury ; for the contact of a heterogeneous 

 body seems to favour the transition of the body from one 

 state of aggregation to another, as I have shown in a memoir 

 on the experiments of Winterl, printed in the Journal qfGeh- 

 len for 1806, vol. i. p. 276—289- 



In some experiments we have found that the water pene- 

 trated between the mercury and the sides of the tube. We 

 have since corrected this inconvenience by cementing to the 

 open extremity of each tube a brass ring, which amalgamates 

 with the mercury, and thus prevents the water from escaping. 



We have also compressed Cyanogen by the same means, and 

 we have found that the liquefaction of this gas begins when 



the air is compressed to oi°f its volume, the thermometer be- 



ing at 23° centigrade, and the barometer at 0.759 metres. 



It would be easy to multiply these experiments, but those 

 which we have given are sufficient to prove that the compres- 

 sion of air and of gases is proportional to the compressing 

 force, however great that force may be, provided they pre- 

 serve their gaseous state, and have lost the caloric developed 

 by their compression. These researches, therefore, have only 

 served to confirm the opinions of the most distinguished phi- 

 losophers of our times upon this subject; but, as there were 

 still others who entertained an opposite opinion, we have not 

 considered the publication of our experiments as altogether 

 useless. 



, The compression of fluids is, as far as we have discovered, 

 subject to the same law of being proportional to the compres- 

 sing forces. We may, therefore, suppose, that gases, reduced 

 to the state of liquids, begin again to follow the same law 

 which they obeyed in their gaseous state. It is also probable, 

 that liquids, after being converted into solids, are subject to 



