ih 
Prof. Horsford on the Permeability of Metals to Mercury. 307 
Upon examining the bars where in contact with the mercury 
they were corroded and lead was found dissolved in the mercury. 
More lead might have dissolved from one bar than the other. 
Another experiment made to determine the expansion of a bar 
of lead, by the absorption of mercury, to which reference will 
be made below, confirms the opinion of higher specific gravity 
of the amalgam 
oe What is the velocity of transmission of mercury through 
It was observed by Prof. Henry that the progress of mercury 
was more rapid in cast than in hammered lead. Upon noting 
the progress from day to day, most unexpected results have pre- 
Serited themselves. In a vertical bar with the 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 0° sb seven inches, it is not one 
thousandth as rapid as at the on 
A hollow bar of lead of 4th ied calibre was erected in a cup 
of mercury. The latter metal rose 
In 6 hours, 2 ; ; ‘ 0-062 mm. 
** 18 hours more, . ; , one = | 
oS day ee a ORE 
' Ss 2 One * 
“ ee fs O01 «, 
“118 9 . .s Ou ™ 
a3 5 ce ‘“ c 0-007 “ 
6 53 6c ts ; 0-006 “ 
“ce 53 “c cc * OoLZ « 
Total, 313 0: 155* 
In two cast bars it rose somewhat more rapidly, and to a total 
greater height. In one (a) the velocities were as follows. 
In 24 hours, ; ‘ j ; 0-085 mm. 
_ “ 24 hours more, . : ; . 0010 
* segeys Skanes ; ome ss 
c 90 ¢ L i 
“& 53 ‘ O-U2L 6c 
eee, SM al 6c 0-005 * 
Total, 234 « 0177 
“essai hse sedan Sin li mime iain cent -—Lieeay Raacaaacachaeal-- tal 
* The mercury arose in a second similar hollow bar,— 
In 24 hours, b. ciehase “es = 
“6 days more, - - ti » : ootd 
digycia ke anienoged al cele ool 
Qebestriasen ae mtrted with mre at a sere te of 
its mercury by evapo 
