146 WRITINGS OP JOSEPH HENRY. [1839 



CAPILLARY TRANSMISSION THROUGH SOLIDS. 



(Proceedings of the American Philosophical Society, vol. i, pp. 82, 83.)* 

 March 15, 1839. 



Professor Henry made a verbal communication relating to 

 a phenomenon of capillary action which had fallen under 

 his notice. 



A lead tube of about half an inch in diameter and eight 

 inches long happened to be left with one end immersed in 

 a cup of mercury, and on inspection a few days afterwards 

 it was observed that the mercury had disappeared from the 

 cup, and was found on the floor at the other end of the tube. 

 Struck with the phenomenon, I again filled the cup with 

 mercury; the next morning the same effect was exhibited. 

 The mercury had again passed over through the tube, ap- 

 parently like water through a capillary siphon, and was 

 again found on the floor. 



On cutting the tube into pieces, it was evident that the 

 mercury had not passed along the hollow axis, but had ap- 

 parently been transmitted through the pores of the solid 

 metal. To determine this, a lead rod of about seven inches 

 long and a quarter of an inch in diameter was bent into 

 the form of a siphon. The shorter leg was immersed in a 

 watch-glass filled with mercury, and a similar glass placed 

 under the end of the longer leg, to receive the metal which 

 might pass over. At the end of twenty-four hours a globule 

 of mercury was perceived at the lower end; and in the 

 course of five or six days all the mercury passed over, leav- 

 ing a crop of beautiful arborescent crystals of an amalgam 

 of lead in the upper glass. 



The mercury did not pass along the surface of the wire, 

 since the lead exhibited, externally, but little change of ap- 

 pearance, although the progress of the penetration could be 

 traced by a slight variation of the color of the oxide on the 

 surface. 



The action is much influenced by the texture of the lead. 

 When a rod of cast lead, of the same size and form, was 



* [Ke-printed in Silliman's American Journal of Science, December, 1839, 

 vol. XXXVIII, pp. 180, 181.] 



