178 



MR. R. ROUTLEDGE ON THE 



tube with a syringe, by which air could be forced into the 

 apparatus ; and the amount of the pressure was measured 

 by a column of mercury in an open manometer. There 

 was some difficulty in measuring the volume, owing to the 

 occasional escape of bubbles of gas, which caused abrupt 

 alterations of the level. The table also contains a column 

 of volumes calculated on the supposition that the amalgam 

 is a mere mixture of fluid mercury and gas, allowance 

 being made for the pressure on the gas due to the column 

 of mercury in the amalgam itself. The extreme case was 

 assumed, namely that this additional pressure is repre- 

 sented by a column of mercury half the height of the 

 amalgam. 



Five points deduced from the mean results of experi- 

 ments 15 to 24 having been laid down in relation to rec- 

 tangular axes, the curve (1) which passed through them 

 is represented in the diagram, which shows also the curve 



Ph 



1 



• 

 1 





w 



1 



i 



j 



Yol of Mercuryj 







» 







Volumes. 



(2) through five points representing the calculated volumes, 

 and a line (3) representing volumes corresponding to the 

 pressures which were applied to the top of the columns of 

 amalgam. 



The diagram and figures sufficiently show that the com- 

 pressibility of the amalgam agrees nearly with the supposi- 

 tion of its being a mixture of gas and mercury, but that it 

 is somewhat less compressible. This, no doubt, is owing 

 chiefly, if not entirely, to its want of fluidity. 



