CHEMICAL SCIENCE. 183 



metals. Prof. Henry modified the experiment of Daniel, in the case 

 of lead, giving to the bar the form of a syphon, one end only of which 

 was immersed in the mercury. He discovered the beautiful fact that 

 mercury may not only be carried through the bar in this form, but that 

 it will drop from the longer division of the bar, thus exhibiting the 

 syphon experiment, employing a solid bar for the tube, and mercury 

 for the liquid. These phenomena had been carefully examined and 

 repeated by Prof. H., with the following results. It is uncertain 

 whether the bars used for the transmission of the mercury increase in 

 specific gravity, after cleaning, or not. Conflicting results were 

 obtained. 



In regard to the velocity of transmission, it was observed, by Prof. 

 Henry, that the progress of mercury in the lead was much more 

 rapid in cast than in hammered lead. Upon noting the progress from, 

 day to day, most unexpected results have presented themselves. In a 

 vertical bar, with mercury at the bottom, the progress is at first rapid. 

 It diminishes in velocity, however, from day to day, until, after 

 several months, having reached a height of between six and seven 

 inches, it is not one thousandth as rapid as at the outset. The mer- 

 cury rose in another, in 69 days, a little more than six inches. It con- 

 tinued to rise with a progress perceptible only after several days. This 

 was drawn lead pipe. In two cast bars it rose somewhat more rapidly, 

 and to a total greater height, thus confirming the result already 

 quoted from Prof. Henry. 



To ascertain if this moderate elevation was influenced in any degree 

 by gravitation, several experiments were made. Mercury was pre- 

 sented at the top of a bar 0.80 m in length. Its descent was astonish- 

 ingly rapid. In ten hours it had penetrated 360 mm . The first quan- 

 tity having all passed into the bar, it ceased to flow. Upon the addition 

 of another portion the flow was resumed. In less than two days 

 the mercury dropped from the bottom. Gravitation evidently facili- 

 tates the transmission of the mercury when flowing from above down- 

 ward. It, of course, opposes its flow from below upward. To ascer- 

 tain the further influence of gravity, a bar, about five inches long, 

 saturated with mercury, was withdrawn from the cup and suspended. 

 After a time a single drop of mercury oozed from the lower end and fell. 

 Whatever the force that held the mercury in the bar, it was not strong 

 enough to retain all of it in opposition to gravity. I should state that 

 from several other saturated bars, of less length, similarly suspended, no 

 mercury escaped. 



The mercury that drops from the bar presents a film upon its sur- 

 face, which, as in a sack of very considerable tenacity, encases the 

 purer metal. Upon analyzing the drop, 1.98 parts of lead were found 

 in it, leaving 98.02, mercury. This result was undoubtedly too low ; 

 it, however, proves the presence of lead in the mercury which has 

 passed through the bar of lead. 



One circumstance might be conceived to modify the flow of mercury 

 amalgam in a given time, to wit, the extent of absorbing surface 

 exposed to the mercury. To ascertain this, two bars of equal length 

 and diameter were taken. They were bent into syphons, and the 



