Compression of Air and other Gases. 



227 



It is only in one of the experiments that we reached to a 

 pressure of eight atmospheres, and we shall now give the results 

 of it. The air in the tube EF was well dried by muriate of 

 lime. The capacity of the tube was measured by mercury, 

 and it contained 1054.8 grammes of it, at the temperature 

 of 20° centigrade. The pressure of the atmosphere on the 

 day of the experiment was 0.7578 metres. The following 

 table shows the ratio which we found between the compression 

 of the air, and the pressure of the mercury : 



The first column of this table gives the numbers obtained 

 by dividing the primitive volume by the volume reduced by 

 the compressing forces, i. e. the densities. The second column 

 gives the compressing forces in numbers, of which unity is the 

 pressure of a column of mercury of 0.7578 metres, equal to 

 the pressure of the atmosphere on the day of the experiment. 

 The third shows the differences between the compressions and 

 the compressing forces, and the fourth shows the ratios of these 

 differences to the compressions. 



It is very difficult in these experiments to determine exactly 

 the volume of air inclosed, since the inferior limit is a curved 

 surface, whose form is often modified by the friction between 

 the mercury and the glass. In all these experiments wc have 



