40 



MOLECULAR ATTRACTION. 



LECT. II. 



Fi g- 2. then to the upper end of the 



tube c, at o, I screwed on the 

 mercurial guage, a, b. 



" The ashes, as they imbibed 

 the water, drew the mercury 

 up 3 or 4 inches, in a few 

 hours, towards z; but the three 

 following days it rose but 1 inch, 

 \ inch, and J, and so less and 

 less, so that in 5 or 6 days it 

 ceased rising. The highest it 

 rose was 7 inches, which was 

 equal to raising water 8 feet." 



In another experiment Hales 

 substituted a tube 8 feet long, 

 and \ inch diameter, filled with 

 red lead, for the tube contain- 

 ing wood ashes, and obtained 

 therewith a rise of 8 inches of 

 mercury.*] 



If we substitute the branch 

 of a tree for the tube filled with 

 wood ashes, [as in fig. 2,] the 

 mercury rises, as in the pre- 



Hales's Apparatus for ascertaining ceding ex p er i ments ma( l e with 



powders. Hales regarded this 

 phenomenon as dependent on 

 a force which he terms " the 

 force of aspiration."! 



Here are some experiments 



the force with which plants imbibe 

 moisture. 



b, the branch. 



r, c, z, the aqueo-mercurial guage. 



t, end of branch from which air 

 escapes. 



x, the cistern of mercury. 



* That portion of the text enclosed between brackets has been intro- 

 duced as a substitute for the less precise statement of Matteucci. I have 

 employed the language of Hales, and have added his figures. J. P. 



t See foot-note, p. 39. 



